Definition: 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.
Input: Problem: how long does a train 105 m long running at the speed of 68 km / hr takes to cross a bridge 90 m length ?
Options: a. 13.9 sec, b. 10.7 sec, c. 17.9 sec, d. 61.9 sec, e. 47.98 sec
Output:
b