A. would be
B. have been
C. are
D. had been
Correct Answer:
Option D – had been
Explanation
The correct answer is ‘D’ because it is a past perfect tense. Option ‘A’ is ‘would be’ which implies the future past tense, option ‘B’ ‘have been’ which means/is a present perfect tense, option ‘C’ are which indicates ‘plural’