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: students at a school were on average 180 cm tall. the average female height was 170 cm, and the average male height was 182 cms. what was the ratio of men to women ?
Options: a. 5: 2, b. 5: 1, c. 4: 3, d. 4: 1, e. 3: 1

Ex Output:
b

Ex Input:
Problem: there are 750 male and female participants in a meeting. half the female participants and one - quarterof the male participants are democrats. one - third of all the participants are democrats. how many of the democrats are female ?
Options: a. 75, b. 100, c. 125, d. 175, e. 225

Ex Output:
c

Ex Input:
Problem: 12.5 * 3.2 * 7.8 = ?
Options: a. 312, b. 435, c. 224, d. 646, e. 742

Ex Output:
a