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: a fort had provision of food for 150 men for 45 days. after 15 days, 10 men left the fort. the number of days for which the remaining food will last, is :
Options: a. 32, b. 37 1 / 4, c. 42, d. 54, e. 45
Example Output: a

Example Input: Problem: car x began traveling at an average speed of 35 miles per hour. after 72 minutes, car y began traveling at an average speed of 49 miles per hour. when both cars had traveled the same distance, both cars stopped. how many miles did car x travel from the time car y began traveling until both cars stopped ?
Options: a. 105, b. 120, c. 140, d. 147, e. 168
Example Output: a

Example Input: Problem: in the storage room of a certain bakery, the ratio of sugar to flour is 5 to 5, and the ratio of flour to baking soda is 10 to 1. if there were 60 more pounds of baking soda in the room, the ratio of flour to baking soda would be 8 to 1. how many pounds of sugar are stored in the room ?
Options: a. 600, b. 1200, c. 1500, d. 1600, e. 2400
Example Output:
e