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.
My sister didn’t leave the house key. As a result, I can’t be cooking lunch now.
A.If my sister have left the house key, I could have been cooking lunch now.
B.If my sister had left the house key, I could have been cooking lunch now.
C.If my sister had left the house key, I could be cooking lunch now.
D.If my sister left the house key, I could be cooking lunch now.