Since "stone" is a noun that means "small rock," we need to find another noun that also means "small rock." While "mountain" may seem like a good answer because mountains are made of stone, "mountain" doesn't mean the same thing as "stone," so it can't be the correct answer. Since "pebble" is a noun that means "a small stone worn smooth by sand or water," "pebble" is the correct answer.

The word pass can be substituted for the word permit to maintain meaning of the sentence.  

Grocery store and market both can be interchanged to keep the same meaning for the sentence.

“Saga” is a noun that means “a long story,” so we need to pick out an answer choice that means something like “a long account.” That means that “gossip” cannot be the correct answer, because “gossip” means “casual or unconstrained conversation or reports about other people, typically involving details that are not confirmed as being true,” which is quite different in meaning from “saga.” “Story,” however, is a noun that can mean “an account of imaginary or real people and events,” and because “story” is the answer choice closest in meaning to “saga,” “story” is the correct answer.

“Castle” is a noun that means “a large building or group of buildings fortified against attack with thick walls,” so we need to pick out an answer choice that means something like “a large building fortified against attack.” That means that neither “moat,” nor “drawbridge” or “tower” can be the correct answer, because while each of these words refers to a part of a castle, none is a synonym of “castle.” “Fortress,” however, is a noun that can mean “a military stronghold, esp. a strongly fortified town fit for a large garrison” or “a heavily protected and impenetrable building,” and because “fortress” is the answer choice closest in meaning to “castle,” “fortress” is the correct answer.

“Melody” is a noun that means “a sequence of single notes that is musically satisfying,” so we need to pick out an answer choice that means something like “a sequence of single notes.” That means that “orchestra” cannot be the correct answer, because while an orchestra might play a melody, “orchestra” does not mean “melody.” “Song,” however, is a noun that means “words set to music,” and because “song” is the answer choice closest in meaning to “melody,” “song” is the correct answer.

"Break" could replace "crack" to maintain a similar meaning.

An "outfit" is a set of clothes; a prison is a place to hold criminals; disease is an illness; a cabin is a type of home; and vegetable is a type of food.

A "stream" is a narrow river; an ocean is a large body of water; a desert is a place that is very dry and is covered in sand; soda is a type of carbonated beverage; and dessert is a type of sweet food commonly eaten after dinner.

An "infection" is a disease; a victory is when you win; a ceremony is a special occassion; an argument is a disagreement; and a group is a number of people together.