Guide and direct are synonyms, and reduce and decrease are synonyms. The answer is not choice b or d because neither means the same as reduce. (Choice c) is incorrect because increase is the opposite of reduce.
Careful and cautious are synonyms (they mean the same thing). Boastful and arrogant are also synonyms. The answer is not (choice b) because humble means the opposite of boastful. The answer is not choice c or d because neither means the same as boastful.
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