Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

[EX Q]: Problem: a train of 25 carriages, each of 60 meters length, when an engine also of 60 meters length is running at a speed of 60 kmph. in what time will the train cross a bridge 1.0 km long ?
Options: a. 2.5, b. 3, c. 5, d. 7, e. 9
[EX A]: a

[EX Q]: Problem: a bag contains 21 toys numbered 1 to 21. a toy is drawn and then another toy is drawn without replacement. find the probability that both toys will show even numbers.
Options: a. 5 / 21, b. 9 / 42, c. 6 / 22, d. 4 / 21, e. 3 / 21
[EX A]: b

[EX Q]: Problem: a train 360 m long runs with a speed of 45 km / hr. what time will it take to pass a platform of 390 m long ?
Options: a. 38 sec, b. 35 sec, c. 44 sec, d. 40 sec, e. 60 sec
[EX A]:
e