A River 100 Mile Wide Flows with a Constant Speed of 1

A river 1.00 mile wide flows with a constant speed of 1.00 mi/h.A man can row a boat at 2.00 mi/h.He crosses the river in a direction that puts him directly across the river from the starting point,and then he returns in a direction that puts him back at the starting point in the shortest time possible.The travel time for the man is

A) 2.00 h.
B) 1.15 h.
C) 1.00 h.
D) 1.33 h.
E) 0.67 h.