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.

Problem: two trains of length 180 m and 280 m are running towards each other on parallel lines at 42 kmph and 30 kmph respectively. in what time will they be clear of each other from the moment they meet ?
Options: a. 22 sec, b. 23 sec, c. 76 sec, d. 20 sec, e. 66 sec
b