Explanation
In this vocabulary item, Shrewd is the closest synonym of Astute, so option B is correct. The word Astute and the word Shrewd share the same central sense in the context tested by the question, although usage, tone and grammatical form should still be checked before substituting one for the other. A synonym is not required to be identical in every possible sentence; it must preserve the intended meaning in the relevant context. Here, replacing Astute with Shrewd keeps the core idea intact without reversing the tone or changing the action, quality or state expressed by the target word. The alternatives Deduce, Desire and Lure do not express the same central meaning as Astute. This distinction matters because competitive examinations often place one accurate synonym beside three familiar but contextually unsuitable words. To verify Astute independently, identify its part of speech, state a short definition, and place both Astute and Shrewd in the same simple sentence. If the sentence retains its essential meaning and grammatical structure, the synonym relationship is supported. Learners should revise Astute together with Shrewd, a brief usage cue and the contrasting distractors.