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 theater box office sold an average ( arithmetic mean ) of 63 tickets per staff member to a particular movie. among the daytime staff, the average number sold per member was 78, and among the evening staff, the average number sold was 60. if there are no other employees, what was the ratio of the number of daytime staff members to the number of evening staff members ?
Options: a. 2: 3, b. 1: 4, c. 1: 5, d. 6: 11, e. 4: 7

Ex Output:
c

Ex Input:
Problem: the cash realised on selling a 14 % stock is rs. 109.25, brokerage being 1 / 4 % is ?
Options: a. 366, b. 106, c. 102, d. 109, e. 122

Ex Output:
d

Ex Input:
Problem: 3 friends had dinner at a restaurant. when the bill was received, akshitha paid 3 / 4 as much as veena paid and veena paid 1 / 2 as much as lasya paid. what fraction of the bill did veena pay ?
Options: a. 4 / 15, b. 3 / 12, c. 3 / 11, d. 3 / 10, e. 3 / 14

Ex Output:
a