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: Consider Input: Problem: ages of two persons differ by 20 years. if 6 year ago, the elder one be 3 times as old the younger one, find their present age
Options: a. 12,28, b. 14,30, c. 16,36, d. 18,34, e. 19,34

Output: c


Input: Consider Input: Problem: in 10 years, a will be twice as old as b was 10 years ago. if a is now 5 years older than b the present age of b is
Options: a. 37, b. 38, c. 39, d. 35, e. 41

Output: d


Input: Consider Input: Problem: a train which has 430 m long, is running 45 kmph. in what time will it cross a person moving at 9 kmph in same direction ?
Options: a. 56 sec, b. 43 sec, c. 36 sec, d. 29 sec., e. 19 sec.


Output: b