Explanation
In this vocabulary item, Perpetual is the closest synonym of Eternal, so option D is correct. The word Eternal and the word Perpetual 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 Eternal with Perpetual keeps the core idea intact without reversing the tone or changing the action, quality or state expressed by the target word. The alternatives Continuous, Harmless and Hopelessness do not express the same central meaning as Eternal. This distinction matters because competitive examinations often place one accurate synonym beside three familiar but contextually unsuitable words. To verify Eternal independently, identify its part of speech, state a short definition, and place both Eternal and Perpetual in the same simple sentence. If the sentence retains its essential meaning and grammatical structure, the synonym relationship is supported. Learners should revise Eternal together with Perpetual, a brief usage cue and the contrasting distractors.