Question

They did not do the sum .... ( add a tag question​

Answer 1

Explanation:

Question tags are used in a sense that contradicts the rest of the sentence. Moreover, the verb remains the same without any change in tense. Since the rest of the sentence is in negative, the question tag should be positive. Hence, Option D is correct. The rest of the options either have the same sense as the sentence or use a different verb. Hence, these are incorrect.