Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.
I did not see Susan off at the airport. I feel bad about it now.
A. I could have seen Susan off at the airport.
B. If only I had seen Susan off at the airport.
C. That I did not see Susan off at the airport escapes me now.
D. It suddenly dawns on me that I should have seen Susan off at the airport.