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: an article is bought for rs. 675 and sold for rs. 900, find the gain percent ?
Options: a. 33 1 / 8 %, b. 33 9 / 3 %, c. 33 1 / 3 %, d. 93 1 / 3 %, e. 33 2 / 3 %

Ex Output:
c


Ex Input:
Problem: last year elaine spent 20 % of her annual earnings on rent. this year she earned 35 % more than last year and she spent 30 % of her annual earnings on rent. the amount she spent on rent this year is what percent of the amount spent on rent last year ?
Options: a. 202.5, b. 194.5, c. 197.5, d. 182.5, e. 177.5

Ex Output:
a


Ex Input:
Problem: in township k, 1 / 5 of the housing units are equipped with cable television. if 1 / 10 of the housing units, including 1 / 3 of those that are equipped with cable television, are equipped with videocassette recorders, what fraction of the housing units have neither cable television nor videocassette recorders ?
Options: a. 23 / 30, b. 11 / 15, c. 7 / 10, d. 1 / 6, e. 2 / 15

Ex Output:

a