Rule: Vocabulary for Central Issues. The sentence is identifying the most essential or core part of the problem. 'Crux' means the decisive or most important point at issue. It correctly points to the central cause of the problem. Option (a) 'periphery' means the outer edge. Options (b) 'consequence' and (d) 'outcome' refer to the results of the problem, not its core.

Rule: Legal Vocabulary and Redundancy. A charge of 'perjury' means the witness lied under oath. The reflexive verb 'to perjure oneself' means to willfully tell an untruth when giving evidence to a court. So, she 'perjured herself'. While this makes the second half of the sentence slightly redundant, it is the only grammatically and logically correct option. Options (a) 'validated', (b) 'vindicated', and (c) 'corroborated' are all positive terms about proving something to be true or correct, the opposite of perjury.

Rule: Metaphorical Vocabulary. A 'vibrant and diverse community' is the result of cultures coming together and mixing. 'Confluence' literally means the junction of two rivers, but it is used metaphorically to mean an act or process of merging. It is an excellent word for the coming together of cultures. Options (a) 'segregation', (b) 'isolation', and (d) 'separation' are all antonyms, describing cultures being kept apart.

Rule: Vocabulary of Control. The purpose of a treaty concerning an 'arms race' would be to limit or control it. 'Curb' means to restrain or keep in check. This verb correctly states the goal of the treaty. Options (a) 'exacerbate', (b) 'promote', and (d) 'encourage' all mean to make the arms race worse or more intense.

Rule: Vocabulary of Humor. Humor based on 'subtle wordplay and irony' is dry and intelligent. 'Wry' humor is a type of humor that is dry, mocking, and understated. This is the perfect description. Options (a) 'broad', (b) 'slapstick', and (d) 'obvious' all describe types of humor that are very direct and physical, the opposite of subtle irony.

Rule: Logical Inference. If something 'raises questions' about a person's health, it is usually their failure to appear where they are expected. 'Absence' is the state of being away from a place or person. The CEO's absence would be a notable event that would cause speculation. Options (a) 'presence', (b) 'attendance', and (c) 'arrival' are all the opposite and would not raise questions about health unless he looked unwell.

Rule: Vocabulary of Argumentation. A closing argument is meant to bring all the pieces of evidence together into a coherent whole to persuade the jury. 'Synthesis' is the combination of ideas to form a theory or system. This word accurately describes the function of a closing argument. Option (a) 'refutation' means proving something wrong. Option (b) 'introduction' happens at the beginning. Option (d) 'digression' is a departure from the topic.

Rule: Vocabulary of Lifestyles. 'Voluntary poverty' describes a person who chooses to be poor, often for religious or philosophical reasons. A 'mendicant' is a person, typically a member of a religious order, who lives by begging. While the artist might not be begging, the word captures the essence of choosing a life of poverty. Options (a) 'sybarite', (b) 'bon vivant', and (d) 'hedonist' are all words for people who are devoted to luxury and pleasure.

Rule: Verbs of Accumulation/Spending. The official is building a 'vast fortune'. The verb needed means to gather or accumulate. 'Amass' means to gather together or accumulate (a large amount or number of valuable material) over a period of time. This is the correct verb. Options (a) 'dissipate', (c) 'disperse', and (d) 'expend' are all verbs related to spending or scattering, which is the opposite of accumulating a fortune.

Rule: Vocabulary of Praise/Criticism. Praise that serves as 'a great source of encouragement' must be generous and freely given. 'Unstinting' means given or giving without restraint; unsparing. It perfectly describes generous praise. Options (a) 'scathing', (b) 'censorious', and (d) 'critical' are all words for harsh criticism, not praise.