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 fraudulent dairy guy declares to market his dairy at price range but he combined it with water and therefore benefits 25 %. the percentage of water in the combination is :
Options: a. 20 %, b. 30 %, c. 50 %, d. 35 %, e. 60 %

Output: a


Input: Consider Input: Problem: what is the median of a set of consecutive integers if the sum of nth number from the beginning and nth number from the end is 110 ?
Options: a. 10, b. 25, c. 55, d. 75, e. 100

Output: c


Input: Consider Input: Problem: we bought a total of 90 books at the store. math books cost $ 4 and history books cost $ 5. the total price was $ 390. how many math books did we buy ?
Options: a. 57, b. 60, c. 63, d. 66, e. 69


Output: b