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.
Q: Problem: my grandson is about as many days as my son in weeks, and my grandson is as many months as i am in years. my grandson, my son and i together are 120 years. can you tell me my age in years ?
Options: a. 65, b. 72, c. 44, d. 73, e. 89
A:
b