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.

The director guided us through the museum. He gave us a specific explanation.

A. While the director was guiding us through the museum, he gave us a specific explanation

B. The director guided us through the museum and was giving us a specific explanation

C. Guiding us through the museum, a specific explanation was given to us by the director

D. The director guided us through the museum while a specific explanation was given to us