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 bag has 9 green balls and 23 pink balls. how many green balls should be added to the bag so that the ratio of green balls and pink balls in the bag becomes 1: 1 ?
Options: a. 10, b. 11, c. 12, d. 13, e. 14

Ex Output:
e


Ex Input:
Problem: 3 ltr of water is added with 9 ltr of a solution containing 57 % of alcohol in the water. the % of alcohol in the new mixture is ?
Options: a. 41.5 %, b. 42.75 %, c. 43 %, d. 45 %, e. 45.75 %

Ex Output:
b


Ex Input:
Problem: tammy climbed a mountain in two days. she spent a total of 14 hours climbing the mountain. on the second day, she walked at an average speed that was half a kilometer per hour faster, but 2 hours less than what she walked on the first day. if the total distance she climbed during the two days is 52 kilometers, how many e kilometers per hour did tammy walk on the second day ?
Options: a. 3, b. 3.5, c. 4, d. 4.5, e. 6

Ex Output:

c