Pipes A, B and C can fill a tank in 15, 30 and 40 hours, respectively. Pipes A, B and C are opened at 6 a.m., 8 a.m. and 10 a.m., respectively, on the same day. When will the tank be full?

A

3:20 p.m.

B

11:20 p.m

C

7:20 p.m

D

5:20 p.m