Two trains each 210m in length each, are running on two parallel lines in opposite directions. If one goes at the speed of 90km/h while the other travels at 85km/h. how long will it take for them to pass each other completely.	Select the correct option:
A) 3 sec B) 2.6 sec C) 3.6 sec D) 8.6 sec E) 7.6 sec

Rationale: "explanation : d = 210 m + 210 m = 420 m rs = 90 + 85 = 175 * 5 / 18 = 243 / 5 t = 420 * 5 / 243 = 8.6 sec answer : option d"
Answer: D