You will be given a definition of a task first, then some input of the task.
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: in what time will two trains cross each other completely, which are running on the same parallel lines in opposite directions, each train running with a speed of 90 kmph being 160 m and 140 m in length respectively ?
Options: a. 5.6 sec, b. 6.2 sec, c. 6.0 sec, d. 7.2 sec, e. 6.8 sec
Output:
c