In what time will a train 100 m long cross an electric pole, it its speed be 72 km/hr?  Select the correct option.
A) 2.5	B) 5	C) 2.4	D) 2.8	E) 2.1

Rationale: "speed = 72 * 5 / 18 = 20 m / sec time taken = 100 / 20 = 5 sec . answer : b"
Answer: B