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: when positive integer n is divided by 3, the remainder is 1. when n is divided by 7, the remainder is 5. what is the smallest positive integer k such that k + n is a multiple of 21 ?
Options: a. 2, b. 4, c. 6, d. 8, e. 10
Example Output: a

Example Input: Problem: maxwell leaves his home and walks toward brad ' s house. one hour later, brad leaves his home and runs toward maxwell ' s house. if the distance between their homes is 14 kilometers, maxwell ' s walking speed is 4 km / h, and brad ' s running speed is 6 km / h. what is the total time it takes maxwell before he meets up with brad ?
Options: a. 2, b. 4, c. 5, d. 6, e. 8
Example Output: a

Example Input: Problem: a statue is being carved by a sculptor. the original piece of marble weighed 190 kg. in the first week 25 percent is cut away. in the second week 15 percent of the remainder is cut away. in the third week the statue is completed when 10 percent of the remainder is cut away. what is the weight of the final statue ?
Options: a. 105 kg, b. 103 kg, c. 109 kg, d. 125 kg, e. 117 kg
Example Output:
c