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: if x ^ 2 – 3 x = 18, then one possible value of x – 4 =
Options: a. - 9, b. - 5, c. - 3, d. - 1, e. 2

Ex Output:
e


Ex Input:
Problem: a student took 5 papers in an examination, where the full marks were the same for each paper. his marks in these papers were in the proportion of 6: 7: 8: 9: 10. in all papers together, the candidate obtained 60 % of the total marks then, the number of papers in which he got more than 50 % marks is
Options: a. 1, b. 3, c. 4, d. 5, e. 7

Ex Output:
c


Ex Input:
Problem: in a store, the total price for 25 shirts is $ 400 and the total price for 75 sweaters is $ 1500. by how much does the average ( arithmetic mean ) price of a sweater exceed that of a shirt in this store ?
Options: a. $ 1, b. $ 2, c. $ 3, d. $ 4, e. $ 5

Ex Output:

d