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 shopkeeper sold 30 articles at the cost price of 35 articles. then find the profit % or lost %
Options: a. 12 %, b. 15 %, c. 16.67 %, d. 18 %, e. 22 %

Ex Output:
c

Ex Input:
Problem: the total age of a and b is 12 year more than the total age of b and c. c is how many years younger than a ?
Options: a. 12, b. 24, c. data inadequate, d. none of these, e. 34

Ex Output:
a

Ex Input:
Problem: at the end of the day, february 14 th, a florist had 90 roses left in his shop, all of which were red, white or pink in color and either long or short - stemmed. a third of the roses were short - stemmed, 15 of which were white and 10 of which were pink. the percentage of pink roses that were short - stemmed equaled the percentage of red roses that were short - stemmed. if none of the long - stemmed roses were white, what percentage of the long - stemmed roses were red ?
Options: a. 20 %, b. 75 %, c. 50 %, d. 33.3 %, e. 80 %

Ex Output:
d