"Mirth" is a noun that means "amusement, especially as expressed in laughter," so we need to pick out a noun that means something like "amusement." "Depression," then, cannot be the correct answer, because "depression" means " severe despondency and dejection, typically felt over a period of time and accompanied by feelings of hopelessness and inadequacy," making it an antonym, not a synonym, of "mirth." "Gaiety," however, is a noun that can mean "the state or quality of being lighthearted or cheerful" or "merrymaking or festivity," and because "gaiety" is the answer choice closest in meaning to "mirth," "gaiety" is the correct answer.

"Outcome" is defined as something that comes about as an effect or end, so "conclusion" is the best match. None of the other answer choices are close in meaning to "outcome": "commencement" means beginning or a ceremony marking the graduation of a group of students; "encumbrance" means burden; "sententious" means sanctimonious or pompous; and "peril" means immediate and serious danger.

"Dread" is defined as great fear, especially in the face of approaching harm, so "phobia," which means a psychological fear of something specific, is the best choice. None of the other answer choices are close in meaning to "dread": "contentment" means satisfaction; "captivation" means fascination or attraction; "facade" means the front face of a building or a false front or appearance; and "hoax" means a deception, often perpetrated on a large scale to fool many people or the public.

An "outing" is a trip or an adventure, so "trip" is the correct answer. None of the other answer choices are close in meaning to "outing": "fortitude" means bravery; "lull" means a pause or break in activity; "abundance" means plentifulness or a great quantity of something; and "compensation" means payment or salary.

"Hoax" is defined as an act intending to trick or deceive, so "joke" is the best match.

Finesse means refinement or a polished way of speaking or acting, so "refinement" is the correct answer.

"Mettle" is defined as strength of spirit, so "courage" is the best match. "Timidity," which means lack of courage, is the opposite.

"Calamity" is defined as catastrophe or disaster, so the best choice would be "catastrophe." "Boon," which means benefit or blessing, is an opposite.

A "mandate" is an order. The best choice is "decree" because it shares the same meaning. Considering the other choices, "day" is the period of time during which the sun is above the horizon, a "chronicle" is a record of events from start to finish, and "breach," when used as a noun, means an act of breaking a rule or agreement or a gap in a wall.

"Audio" is another word for sound. "Sound" is the best choice because it is a part of the definition of "audio." Considering the other options, an "audience" is a group of people who are watching or listening to a particular event, "audacious" means daring or reckless, and "wise" means characterized by having knowledge and good judgement.