Woman: I don't think we should have told T

问题：

Woman: I don't think we should have told Tom about the surprise party for Lucy.Man: It's all right. He promised not to tell, and he doesn't make promises lightly.Question: What does the man mean

A．Tom has arranged a surprise party for Lucy.

B．Tom will keep the surprise party a secret.

C．Tom and Lucy have no secrets from each other.

D．Tom didn't make any promise to Lucy.