Choose the most appropriate antonym of the highlighted word.
The cow happily recovered, which the widow entirely attributed to the efficacy of her pastor's prayer.

Correct option is A

The correct antonym of the given word is (a) Inadequacy.
Given word: Efficacy
Meaning: The ability to produce a desired or intended result.
Hindi Meaning: प्रभावकारिता
Antonym: Inadequacy
Meaning: Lack of effectiveness or ability to produce the desired result.
Hindi Meaning: अपर्याप्तता
Synonyms: Potency, effectiveness, efficiency, capability.
Antonyms: Inadequacy, weakness, impotence, inefficiency.
Meanings of all options:
Inadequacy: Lack of effectiveness.
Potency: Power or effectiveness.
Virtue: Moral goodness.
Effect: Result or outcome of an action.