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: in town x, 64 percent of the population are employed, and 47 percent of the population are employed males. what percent of the employed people in town x are females ?
Options: a. 16 %, b. 46 %, c. 32 %, d. 24 %, e. 52 %

Ex Output:
d

Ex Input:
Problem: car z travels 50 miles per gallon of gasoline when driven at a constant rate of 45 miles per hour, but travels 20 percent fewer miles per gallon of gasoline when driven at a constant rate of 60 miles per hour. how many miles does car z travel on 10 gallons of gasoline when driven at a constant rate of 60 miles per hour ?
Options: a. 320, b. 375.2, c. 400, d. 408.3, e. 440

Ex Output:
c

Ex Input:
Problem: what is the units digit of 2222 ^ ( 555 ) * 3333 ^ ( 222 ) ?
Options: a. 0, b. 2, c. 4, d. 6, e. 8

Ex Output:
b