A boy plans to paddle a rubber raft across a river to the east bank while the current flows down river from north to south at 1 m/s. He is able to paddle the raft at 1.5 m/s in still water. In what direction should he head the raft to go straight east across the river to the opposite bank?
(a) Directly to the east
(b) South of east
(c) North of east 

(d) North
(e) South