The speed of a boat in still water is 12 km/hr and the rate of current is 4 km/hr. The distance travelled downstream in 18 minutes is	Choose one
A) 1.6 km	B) 2 km	C) 3.6 km	D) 4.8 km	E) none of these

Rationale: "explanation : speed downstreams = ( 12 + 4 ) kmph = 16 kmph . distance travelled = ( 16 x 18 / 60 ) km = 4.8 km option d"
Answer: D