A person can swim in still water at 4 km/h. If the speed of water 2 km/h, how many hours will the man take to swim back against the current for 16km?
Choose the correct option:
A) 3 B) 6 C) 8 D) 9 E) 7

Rationale: "m = 4 s = 2 us = 4 - 2 = 2 d = 16 t = 16 / 2 = 8 answer : c"
Answer: C