"Uncertain" means unknown or unsure, so "unsure" is the correct answer. None of the other answer choices are close in meaning to "uncertain": "complex" means complicated or having many different parts; "frequent" means occurring repeatedly in a relatively short amount of time; "profitable" means lucrative or capable of making a lot of money; and "secretive" means hidden or concealed.

The word “indispensable” consists of the negative prefix “in-,” which means “not,” and the word “dispensable,” so we can infer that it means “not dispensable.” That inference would be correct, as “indispensable” is an adjective that means “absolutely necessary,” so we need to pick out a word that means something like “necessary.” “Superfluous,” then, cannot be the correct answer, because “superfluous” means “unnecessary, especially through being more than enough,” making it an antonym, not a synonym, of “indispensable.” “Essential,” however, is an adjective that means “absolutely necessary; extremely important,” and because “essential” is the answer choice closest in meaning to “indispensable,” “essential” is the correct answer.

“Insignificant” is an adjective that can mean “too small or unimportant to be worth consideration,” “without power or influence” when used of a person, or “meaningless.” So, we need to pick out an answer choice that means something like “unimportant,” “without power,” or “meaningless.” That means that “noteworthy” cannot be the correct answer, because “noteworthy” means “interesting, significant, or unusual,” making it an antonym, not a synonym, of “insignificant.” “Petty,” however, is an adjective that means “ of little importance; trivial,” and because “petty” is the answer choice closest in meaning to “insignificant,” “petty” is the correct answer.

"Indifferent" means apathetic or not caring, so "apathetic," an adjective that means unconcerned or unemotional, is the correct answer. For clarification, "careless" means negligent, "jocular" means good-humored, joking, or playful, and "aggressive" and "belligerent" are synonyms that each mean hostile and confrontational.

"Submerged" means underwater; Dry means without water; Brief means temporary; Mandatory means required; and Tedious means boring.

"Ubiquitous" means existing or being everywhere.

Words you may not know: 

• "Scarce" means not abundant.
• "Urbane" means having sophistication or elegance, a quality often associated with cities. The root "urb-" (as in urban) means city.

"Convivial" is an adjective that means "friendly, lively, and enjoyable" when being used to describe an atmosphere or event, and "cheerful and friendly; jovial" when being used to describe a person. So, we need to pick out an adjective that means something like "friendly." "Hostile," then, cannot be the correct answer, because "hostile" means "unfriendly; antagonistic," making it an antonym, not a synonym, of "convivial." "Affable," however, is an adjective that means "friendly, good-natured, or easy to talk to," and because "affable" is the answer choice closest in meaning to "convivial," "affable" is the correct answer.

"Incompetent" means unskilled or incapable.

"Circumspect" is derived from the Latin for to look around, so the best meaning is "cautious," as in, "The administration was very circumspect about the responses they gave to the media's questions."

"Superfluous" means extra or not required, so "extra" is the correct answer. "Superfluous" is an antonym of "essential," which means necessary or required. For clarification, "fundamental" means basic, important, or essential, and "fey" means supernatural or mystical.