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 12 machine can finish a job in 40 days, then how many more machines would be needed to finish the job in one - fourth less time ?
Options: a. a. 4, b. b. 8, c. c. 10, d. d. 12, e. e. 16
Example Output: a

Example Input: Problem: he average of 10 numbers is 23. if each number is increased by 4, what will the new average be ?
Options: a. 26, b. 27, c. 88, d. 99, e. 12
Example Output: b

Example Input: Problem: in simple interest what sum amounts of rs. 1120 / - in 4 years and rs. 1200 / - in 5 years ?
Options: a. rs. 500, b. rs. 600, c. rs. 800, d. rs. 900, e. rs. 700
Example Output:
c