The exam questions were too difficult. I didn’t answer most of them.

A. If the questions had been less difficult, I couldn’t have struggled with most of them.

B. If the questions had been less challenging, I might not have had difficulty answering most of them.

C. If the questions had been more manageable, I could have answered most of them.

D. If the questions had been easier, I can have been able to answer most of them.