A man can row his boat with the stream at 16 km/h and against the stream in 4 km/h. The man's rate is?	Choose the correct choice from the following choices:
A) 1 kmph
B) 3 kmph
C) 6 kmph
D) 7 kmph
E) 5 kmph

Rationale: "ds = 16 us = 4 s = ? s = ( 16 - 4 ) / 2 = 6 kmph answer : c"
Answer: C