Rule: Vocabulary of Rulers. A 'cruel' ruler who uses 'fear and intimidation' is known as a tyrant. 'Tyrant' is a cruel and oppressive ruler. This word perfectly fits the description. Options (a) 'benefactor' (one who gives help), (b) 'democrat' (one who believes in democracy), and (d) 'humanitarian' (one who works to help people) are all positive terms for rulers or leaders.

Rule: Legal/Formal Vocabulary. The sentence describes a situation where the bulk of the evidence, though not conclusive, suggests one conclusion. 'Preponderance' means the quality or fact of being greater in number, quantity, or importance. 'Preponderance of the evidence' is a specific legal standard of proof where the evidence is more likely than not to be true. Options (a) 'paucity', (b) 'scarcity', and (d) 'lack' all mean there is not enough evidence, which contradicts the first part of the sentence.

Rule: Vocabulary of Support. A person who 'donates millions' to support the arts is known as a patron. 'Patron' is a person who gives financial or other support to a person, organization, cause, or activity. This is the correct term. Options (a) 'critic', (b) 'detractor', and (d) 'opponent' are all words for people who oppose or speak out against something.

Rule: Economic Vocabulary. Cutting interest rates is a monetary policy tool used to encourage borrowing and spending, with the goal of increasing economic activity. 'Stimulate' means to encourage development, interest, or activity in (something). This is the correct economic term for this action. Options (a) 'stifle', (b) 'hamper', and (d) 'inhibit' are all verbs that mean to hinder or prevent growth.

Rule: Vocabulary of Relationships. The fact that they 'have not spoken to each other since' implies the argument was very bitter and angry. 'Acrimonious' means (typically of speech or a debate) angry and bitter. This word accurately describes a friendship-ending argument. Options (a) 'amicable', (c) 'harmonious', and (d) 'cordial' are all words for friendly and peaceful interactions.

Rule: Vocabulary of Ecosystems. Rainforests are characterized by a dense, upper layer of trees. 'Canopy' is the term for the upper layer or habitat zone, formed by mature tree crowns. This is the correct term for the part of the rainforest being described. Options (b) 'desert', (c) 'tundra', and (d) 'savanna' are different types of biomes, not parts of a rainforest.

Rule: Business Vocabulary. Having a 'significant advantage over its competitors' because of a technology implies exclusive control or possession of it. 'Monopoly' means the exclusive possession or control of the supply of or trade in a commodity or service. This is the correct business term. Options (b) 'prohibition', (c) 'embargo', and (d) 'restriction' are all terms for limiting or banning something, which don't fit the context of gaining an advantage through possession.

Rule: Vocabulary of Communication. Explaining complex theories 'in simple, understandable terms' is the act of clear explanation. 'Exposition' is a comprehensive description and explanation of an idea or theory. This word perfectly describes the professor's skill. Options (a) 'obfuscation' (making something obscure), (c) 'equivocation' (using ambiguous language), and (d) 'complication' (making something more difficult) are all antonyms.

Rule: Verbs of Helping/Harming. A charity organization's purpose is to reduce or lessen suffering. 'Mitigate' means to make less severe, serious, or painful. This is the correct verb for the charity's work. Options (a) 'intensify', (b) 'prolong', and (d) 'increase' are all actions that would make suffering worse, which is the opposite of a charity's mission.

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.