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.

Example 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
Example Output: c

Example Input: Problem: a library branch originally contained 18360 volumes, 30 % of which were fiction novels. 1 / 3 of the volumes were transferred to another location and 1 / 5 of the volumes transferred were fiction novels. what percent of the remaining collection was fiction novels ?
Options: a. 2.5 %, b. 17.67 %, c. 28.3 %, d. 36 %, e. 73.6 %
Example Output: d

Example Input: Problem: working alone, mary can pave a driveway in 4 hours and hillary can pave the same driveway in 3 hours. when they work together, mary thrives on teamwork so her rate increases by 33.33 %, but hillary becomes distracted and her rate decreases by 50 %. if they both work together, how many hours will it take to pave the driveway ?
Options: a. 2 hours, b. 4 hours, c. 5 hours, d. 6 hours, e. 7 hours
Example Output:
a