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 posted the letter. I realized tha...

A. Only after posting the letter did I realize that I had forgotten to put on a stamp

B. Hardly had I realized that I had forgotten to put on a stamp when I posted the letter

C.Not only did I realize that I had forgotten to put a stamp on the letter but I posted it as  well

D. No sooner had I posted the letter than I forgot to put on a stamp