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.

Example Input: Problem: if two dice are thrown together, the probability of getting an even prime number on the dice is
Options: a. 1 / 36, b. 1 / 18, c. 1 / 13, d. 1 / 9, e. 5 / 36
Example Output: a

Example Input: Problem: anand finishes a work in 7 days, bittu finishes the same job in 8 days and chandu in 6 days. they take turns to finish the work. anand on the first day, bittu on the second and chandu on the third day and then anand again and so on. on which day will the work get over ?
Options: a. 3 rd, b. 6 th, c. 9 th, d. 7 th, e. 8 th
Example Output: d

Example Input: Problem: if the simple interest on a sum of money for 2 years at 5 % per annum is rs. 52, what is the compound interest on the same sum at the rate and for the same time ?
Options: a. s. 53.30, b. s. 53.22, c. s. 51.219, d. s. 53.18, e. s. 51.10
Example Output:
a