Two trains 200 m and 150 m long are running on parallel rails at the rate of 40 kmph and 46 kmph respectively. In how much time will they cross each other, if they are running in the same direction? Choose the correct choice from the following options:	A) 72 sec	B) 210 sec	C) 192 sec	D) 252 sec	E) none

Rationale: "solution relative speed = ( 46 - 40 ) kmph = 6 kmph = ( 6 x 5 / 18 ) m / sec = ( 30 / 18 ) m / sec time taken = ( 350 x 18 / 30 ) sec = 210 sec . answer b"
Answer: B