A、Natalie already knows about the surprise party. B、Eugene and Natalie are not good friends. C、Eugene will probably tell Natalie

M: Miss Hanson, thank you for sending me this note. I’m sorry to hear Mary is being a problem.
W: I’m not sure what’s happening to Mary. She’s usually an excellent student. She completes all her work and she’s quiet in class. Then, last month, she just changed.
Q: What can you infer from the conversation?

M: Maybe it wasn’t a good idea to tell Eugene about the surprise party for Natalie this Friday.
W: I’m not worried. He promised not to tell and he doesn’t make promises lightly.
Q: What does the man mean?