Select the most appropriate choice to fill in the blank.
The country ________________ several economic changes in the past two decades.

Correct option is A

The word that can be filled in the blank is ‘underwent’ to make the sentence grammatically and contextually correct. • Underwent is the past tense of undergo, indicating that the country experienced various economic changes in the past. Grammatical Rule involved: Past tense verb usage - To reflect an action that has been completed in the past. • Here, ‘underwent’ is the correct choice as it accurately describes past changes.
Meanings of other given words:
• Had undergone - past perfect tense; not needed here. • Will be undergoing - future tense; incorrect in this context. • Have been undergoing - present perfect continuous; not suitable here. • Thus, only ‘underwent’ is appropriate.