阅读下列文章，选出以下3道题的最佳选项。Tom is ten years old, and he is a very lazy boy. He doesn’t like doing any work. He has to go to school, but he doesn’t study hard there and does as little work as possible. His father and mother are doctors and they hope that their son also become a doctor in the future.But one day Tom says to his mother, “When I finish school, I want to be a dustman（清洁工）.”“A dustman?” his mother asks, and she is very surprised. “Why do you want to become a dustman?”“Because then I only have to work one day a week.” Tom answers.“Only one day a week?” his mother says, “What do you mean? And how do you know?”“Well,” Tom says, “I know that the dustmen who come to our house work on Thursday, because I only see them on that day.”(1) What are Tom’s father and mother?
选项：

A: His father is a doctor and his mother is a nurse.
B: His father is a worker, and his mother is a doctor.
C: His father and mother are doctors.
D: His father is a worker, and his mother is a nurse.