Natural selection is the process by which organisms that survive best pass on their genes, ensuring genetic modification over time. This is always occurring in the natural world. This can be contrasted with artificial selection, which occurs when humans select for certain traits. Bioballistics and biolistics are two terms for the same idea. They refer to the process of using a "gene gun" in order to introduce genetic material into an organism. 

Thus, natural selection is the only option which doesn't involve human intervention.

The acronym GMO stands for “Genetically Modified Organism.” It is used in common parlance to refer to a crop whose genetic structure has been altered to make it more useful and efficient for human purposes. GMOs are often controversial because some scientists claim that their health effects have not yet been realized.

The term “biotechnology” is applied to any technological innovation that is designed to improve the usefulness of plant and animals species for human agricultural purposes. Biotechnology is what drove the population growth of the Green Revolution. It is often controversial, such as in genetically modified organisms.

Genetically Modified Organisms are crops whose genetic makeup has been altered to encourage some positive traits and eliminate some negative traits. These crops, however, are not universally supported. Opponents of GMOs argue that the environmental consequences remain unknown and could be potentially devastating. Even opponents of GMOs recognize their potential to benefit those in areas of economic and food scarcity.

The United States and Brazil together account for almost ninety percent of the world’s production of ethanol fuel and are by far the biggest uses of ethanol to fuel motor vehicles. Brazil’s government has made it an official policy and ethanol usage continues to rise in Brazil.

Genetically-modified organisms are a controversial topic in contemporary agricultural geography. GMO's are crops whose genetic makeup has been altered to encourage positive traits and eliminate negative traits. This leads to a more efficient process and a more reliable product, but has many potential downsides.

“Ethanol” is an ethyl alcohol produced from corn and grain. In recent years it has started to be used to fuel motor vehicles, particularly in the United States. Ethanol is neither used as an antiseptic nor as a form of water treatment.

“Pesticides” are chemicals that are used to treat agricultural crops so as to kill any insects or animals that might try to damage the crop. “Herbicides” are similar but are chemicals that are used to treat agricultural crops so as to kill any plants that might cause a disruption in the growth of the desired product.

Genetic engineering, artificial insemination, and the use of bacteria to make food products are all examples of biotechnology, or the purposeful utilization of biological organisms and/or processes to create or improve products. Hybrid animals bred naturally in the wild are not considered an example of biotechnology.

Organic farming does not use fossil fuels to control insect and plant pests. This means organic farms tend to have a smaller carbon footprint and less reliance on artificial inputs. The downside, however, is that organic farms also require much more physical labor. Thus the correct answer is, "Reduced effort required to cultivate crops."