They said, “It was raining heavily,when they came out of the theatre.”

A. They said that it was raining heavily, when they had come out of the theatre.
B. They said that it had been raining heavily, when they came out of the theatre.
C. They said that it rained when they had come out of the theatre.
D. They said that it had been raining heavily, when they had come out of the theatre.