The prefix "ir-" is a negation prefix, so “irreversible” has the opposite meaning of “reversible.” Since “reversible” means able to be reversed, able to be changed back, then “irreversible” means not able to be changed, or “permanent.” To provide further help, “temporary” is an antonym of “permanent;” “mercurial” means enigmatic, hard to predict; “enigmatic” means mysterious; “lackadaisical” means lazy or careless.

In this question, the word "novel" is being used as an adjective, meaning new or inventive. The only word with a similar meaning is "innovative," which means original or new. "Celebrated" means renowned, while "literary" means having to do with literature or reading, and was meant to throw you off if you had only seen the stem word as a noun (meaning a book-length work of fiction) rather than as an adjective. "Puzzling" means confusing or perplexing.

Primitive means having to do with the early history of the world or of humanity, or simple and relatively undeveloped. "Ancient" means extremely old, so "ancient" is the answer choice closest in meaning to "primitive."

A good example using the word primitive is to describe cooking tools used by early man.  These tools were primitive and were originally used by man to cook.

“Consecutive” means occurring in order, one after the other. This is closest in meaning to “successive.” To provide further help, “incoherent” means not able to be understood; “comparable” means able to be compared, similar; “consensus” means agreement; “proclivity” means tendency of doing something.

“Abrupt” means sudden and unexpected. To provide further help, “outlandish” means bizarre, peculiar, or strange; “dogmatic” means bound by strict, inflexible rules; “miserable” means very sad; “circumstantial” means owed to circumstance, owed to chance.

"Wizened" means dry, shrunken, and wrinkled due to being old, so "gnarled," an adjective that means twisted and rough due to age, is the correct answer.

Something "permanent" will remain a certain way for a long time. The other answer choices have meanings as follows: "partial" means only a part of something; "delayed" means late; and "occasional" means occurring infrequently.

"Urgent" means pressing or immediate, so "pressing" is the correct answer. "Urgent" has a meaning different from that of "repetitive," which means tedious due to repetition,"steady," which means unvarying or consistent; and "unending," which means not having an end or lasting for a very long time.

Something that happens “frequently” happens often, so "frequent" means "often." The word “pesky” means troublesome, like “a pesky wasp”; and “frantic” means hurried or rushed due to being very worried about something.