What do we learn from the conversation?
A)The man was confused about the date of the appointment
B)The man wants to change the date of the appointment
C)The man is glad he's got in touch with the doctor
D)The man can't come for the appointment at 4:15
原文：
W: Hello, this is Dr. Gray's office. We're calling to remind you of your 4:15 appointment for your annual checkup tomorrow.
M: Oh, thanks. It's a good thing you called. I thought it was 4:15 today.