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: 9 years ago i was 5 times as old as my eldest son. today i am 3 times his age. how old am i now ?
Options: a. 45, b. 54, c. 34, d. 58, e. 56
Output:
b