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: a couple who own an appliance store discover that if they advertise a sales discount of 10 % on every item in the store, at the end of one month the number of total items sold increases 15 %. their gross income from sales for one month increases by what percent ?
Options: a. 1.5 %, b. 2.5 %, c. 3.5 %, d. 4.5 %, e. 5.5 %

Ex Output:
c


Ex Input:
Problem: a soccer team played 280 games and won 65 percent of them. how many games did it win ?
Options: a. 182, b. 100, c. 104, d. 150, e. 124

Ex Output:
a


Ex Input:
Problem: the speed of a subway train is represented by the equation z = s ^ 2 + 2 s for all situations where 0 ≤ s ≤ 7, where z is the rate of speed in kilometers per hour and s is the time in seconds from the moment the train starts moving. in kilometers per hour, how much faster is the subway train moving after 7 seconds than it was moving after 5 seconds ?
Options: a. 4, b. 28, c. 15, d. 48, e. 63

Ex Output:

b