Which of the sentences contains both an independent and a dependent clause?

A. He was listening intently to the radio, and he did not hear the doorbell.

B. As she entered the auditorium, she tripped over a backpack that had been

carelessly left in the doorway.

C. Visiting the aquarium turned out to be quite an adventure; I enjoyed it

thoroughly.

D.We understand the environmental concerns of the farming community, but we are aware that business owners have another point of view.