单项选择题

M: I hear you have flexible working system now, Joe.
W: Yes, we have to be in the office by 9 o’clock and may leave anytime after 3 in the afternoon.

When may Joe leave her office by having flexible working system()

A. 9:00 a.m.
B. 9:00 p.m.
C. 3:00 p.m.
D. 1:30 p.m.