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.

Ex Input:
Problem: if the population of a certain country increases at the rate of one person every 15 seconds, by how many persons does the population increase in 25 minutes ?
Options: a. 80, b. 100, c. 150, d. 240, e. 300

Ex Output:
b


Ex Input:
Problem: a shopkeeper sold 30 articles at the cost price of 35 articles. then find the profit % or lost %
Options: a. 12 %, b. 15 %, c. 16.67 %, d. 18 %, e. 22 %

Ex Output:
c


Ex Input:
Problem: i flew my tiny seaplane to visit my mother. on the flight up, i flew at 96 mph. on the way home, i flew 88 mph. what was my average speed for the trip ?
Options: a. 198 mph, b. 110 mph, c. 92 mph, d. 100 mph, e. 99 mph

Ex Output:

c