"Incontrovertible" is an adjective that means "not able to be denied or disputed," so we need to pick out an answer choice that means something like "undeniable." "Unbelievable," while beginning with a negative prefix like both "incontrovertible" ("in-") and "undeniable" ("un-") do, actually means "not able to be believed; unlikely to be true," so it is an antonym of "incontrovertible" and "undeniable." "Irrefutable," however, is an adjective that means "impossible to deny or disprove," and because "irrefutable" is the answer choice closest in meaning to "incontrovertible," "irrefutable" is the correct answer.

The word "equivocal" meansunclear in meaning due to being able to be interpreted in multiple ways.The best choice is "ambiguous," which meanshaving more than one meaning.Something that is ambiguous is unclear because it can have multiple meanings, as is an equivocal statement. Considering the other choices, "equal" meanshaving the same value,"audible" meansable to be heard,and "original" meansneworthe initial one of its kind.

The word "scurrilous" meansoffensive.The best choice is "offensive," as it is a part of the definition of "scurrilous." Considering the other choices, "scamper" meansrun about playfully,"gloomy" meanssaddened,and "clever" meansquick-witted.

The word "vituperative" meansabusive.So "abusive," a word that meanscharacterized by treating someone badly,is the correct answer. Considering the other choices, "neglected" meansnot having received a suitable amount of attention, "criticized" meansjudged harshly by anotherwhen describing something,and "disorganized" meanscareless.

"Paltry" meanshaving little meaning, importance, or worthorvery small or meager. "Insignificant" is the only choice that has a definition similar to that of "paltry."

"Trivial" meansunimportant, so "unimportant" is the synonym.

The word "crucial" refers to something that isnecessary to achieve a certain end. For example, if one more loss will eliminate your team from the baseball championship, then winning the next game is crucial. Basically, we are looking for a word that implies great importance. "Vital," which meansessential, is the best choice here. "Unimportant" is the opposite of the answer that we want, and "extra" implies that something ispresent in addition to a certain quantity and unnecessary, not that it is necessary. Finally, "diminutive" meansshortorunusually small.

If something is pivotal, it means that it isimportant.For example, the last regular football game of a season is pivotal in determining whether the team will play in the semifinals.

Something that is “eminent” iswell-knownorimportant. This is opposed to something that is "imminent," which meansabout to happen. To provide further guidance, "futile" meanspointless; "worthless" meansnot worth anything; "morose" meansmiserable and glum; "novelty" meansinnovation, something original.

"Tangential" is an adjective that means either "diverging from a previous course or line; erratic," or "hardly touching a matter; peripheral." So, we need to pick out an answer choice that means something like "erratic" or "peripheral." "Essential" cannot be the correct answer, then, because "essential" means "absolutely necessary; extremely important," making it an antonym of "tangential," not a synonym. "Nonessential," however, is an adjective that means "not absolutely necessary," and because "nonessential" is the answer choice closest in meaning to "tangential," "nonessential" is the correct answer.