单项选择题

M: I hope that Mr. Wang will be in the office.
W: Well, he usually works from 8:00 a,m. to 5:00 p.m...On Saturdays and Sundays, he works from 9:00a.m. to 12:00 noon.

When will Mr. Wang begin to work on weekends()

A. 5 p.m.
B. 12 noon.
C. 8 a.m.
D. 9 a.m.