The information in the table shows that while many people apply for archaeology jobs at museums and universities, the actual number of jobs is much smaller, so only 8% and 13% of applicants will find those jobs.  This supports the claim that “the demand for these jobs outstrips the number of positions available, making these jobs difficult to get.” This makes " Yes, because the information in the table validates the claim made in the last sentence of the paragraph."  

Among the other answer choices:  "Yes, because the information in the table proves that archaeology professors spend most of their time on teaching and writing" is incorrect as the table shows what types of jobs are available but does not talk about the activities that take place within the “University” jobs column.  "No, because the information in the table shows that most archaeologists apply for jobs at universities" is incorrect because while the table does show that more people apply to universities than any of the other four categories, that doesn’t mean that “most” (more than ½) do.  Also it is perfectly consistent with the author’s point that many people apply to university jobs (that’s “demand”); the author just adds that not many of those jobs exist, and the table also supports that.  And "No, because the information in the table does not specify whether the jobs at museums are curator jobs" is incorrect because, again, the “because” reason here is consistent with the author’s point that there aren’t many jobs as university professors and museum curators. If the very small number of museum jobs were to even include museum jobs that aren’t for curators, that reinforces the point that the jobs people tend to visualize as archaeology jobs aren’t, in fact, what most archaeologists do.

While this table is somewhat related to the topic of earthworms’ impact on soil fertility, note that the passage doesn’t directly link the metrics in the table (corn height, in particular) to soil fertility itself.  Without that direct connection, the table is out of scope of the passage’s subject matter - it’s somewhat related but doesn’t quite fit. That makes choice "No, because the information displayed in the table is not directly referenced by or connected to the passage. 'a good option.

But as in most SAT questions that provide you with Yes/No answer choices that include reasons, this problem is best attacked with process-of-elimination.  With choice "Yes, because it proves that corn can only grow when there are more than 62 worms per square meter.", recognize the extremely strong language in “prove” and “only” - the table does show that for these 7 locations in Manitoba, corn grows and the worm count is above 62 worms per square meter.  But these seven locations don’t prove that that is the only case; there could very well be other corn-growing locations with lower worm counts that just weren’t part of this study. So "Yes, because it proves that corn can only grow when there are more than 62 worms per square meter." has logical problems, and like "No, because the information displayed in the table is not directly referenced by or connected to the passage." alerts you to the topic doesn’t directly connect to the passage, which doesn’t call for proof of worm density in soil.

With "Yes, because it demonstrates that corn grows higher when there are more earthworms in the soil."  the logic of the “because” portion is sound (the table does show that corn grows higher when worm concentration is higher) but the passage doesn’t include language to connect corn height to soil fertility, so this lesson doesn’t directly connect to a main point of the paragraph.

And with "No, because corn is not the only type of plant that should be able to grow in soil fertilized by earthworms.", note that if the table were connected to the passage in language it could very well be helpful - showing that earthworm concentration is the best predictor of corn height could very well make the case that earthworms are extremely influential with regard to soil fertility. The table doesn’t have to prove that this is true for all plants in order for this finding from one type of plant to help demonstrate the case that worms are good for the soil. So "No, because corn is not the only type of plant that should be able to grow in soil fertilized by earthworms." is wrong in that the issue with the table isn’t that it only includes corn, but that the passage doesn’t directly connect the idea of corn height to soil fertility.

Whenever you’re asked whether an author should add a sentence, graph, or table, you should look to see where that addition would go and how well it connects to the rest of the information on either side of it. Here the table would be placed immediately after a discussion of the three characteristics of a niche constructor and immediately before the scope of the passage shifts to focus on the earthworm.  Importantly, none of the organisms in the table would qualify as niche constructors, as none has inspired an evolutionary response, and there is no discussion that directly connects to why such a table would fit: were the author to say that niche construction is quite rare given the narrow definition, for example, or that many organisms dramatically impact their ecosystems even without being niche constructors, this table would have a connection to the passage.  But no such reference exists: the passage is meant to go from the general definition of a niche constructor to several paragraphs talking about the earthworm in particular. So choice "No, because it introduces irrelevant information that disrupts the flow of the passage."  is correct - the table is irrelevant to the discussion that surrounds it.

Among the incorrect choices: "Yes, because it demonstrates that not all organisms fit the three-part criteria of being niche constructors."  is “true” in what it says about the table, but the passage doesn’t have any context that calls for such a discussion. "Yes, because it shows the various ways in which niche constructors benefit other plants and animals." is incorrect, as none of the organisms in the table count as niche constructors.  And "No, because it does not include a varied enough sample of different organism types."  misses the point that the table itself isn’t connected to the context, so it doesn’t matter how many organisms are listed as the table just doesn’t have a place.