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: a and b go around a circular track of length 200 m on a cycle at speeds of 36 kmph and 72 kmph. after how much time will they meet for the first time at the starting point ?
Options: a. 120 sec, b. 198 sec, c. 178 sec, d. 20 sec, e. 276 sec

Output: d


Input: Consider Input: Problem: the ratio of the present age of viju to that of aju is 7: 2. 4 years from now, the ratio of the ages of viju to aju will be 5: 2. what was viju age 5 years ago ? ( rbi assistant 2015 )
Options: a. 24, b. 18, c. 12, d. 16, e. 13

Output: d


Input: Consider Input: Problem: if x + y = 4 and x 2 y 3 + y 2 x 3 = 36, what is the value of xy ?
Options: a. 1, b. 2, c. 3, d. 4, e. 5


Output: d