A、Milk. B、Sleep. C、Exercise. D、Genes. D男士说孩子的父亲身高两米，可以推测他的意思是说遗传起了很大作用，故答案为D。

W: I made a big mistake today. I read a student’s article to the class and pointed his errors out. I meant the whole class to learn from his article. Then I saw he was lowering his head and I realized he was hurt.
M: It is the teacher’s responsibility to point out students’ errors but not in public. For some of the students have a strong sense of self-respect.
Q: What are they mainly talking about?

W: I know why that child is growing so tall at the age of four. His mother requires him to drink a cup of milk every night before going to bed.
M: It may not be the reason. As far as I know, the child’s father is 2 meters tall.
Q: What is the key to the child’s extraordinary height according to the man?