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 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 %
Example Output: c

Example Input: Problem: the average weight of a, b and c is 43 kg. if the average weight of a and b be 48 kg and that of b and c be 42 kg, then the weight of b is :
Options: a. 55 kg, b. 53 kg, c. 49 kg, d. 52 kg, e. 51 kg
Example Output: e

Example Input: Problem: last year a worker saved 6 % of her annual salary. this year, she made 20 % more money than last year and she saved 5 % of her salary. the amount she saved this year was what percent of the amount she saved last year ?
Options: a. 90 %, b. 100 %, c. 110 %, d. 120 %, e. 130 %
Example Output:
b