TASK DEFINITION: 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.
PROBLEM: Problem: a merchant marks goods up by 80 % and then offers a discount on the marked price. the profit that the merchant makes after offering the discount is 35 %. what % discount did the merchant offer ?
Options: a. 20 %, b. 25 %, c. 30 %, d. 35 %, e. 40 %

SOLUTION: b

PROBLEM: Problem: what is the greatest positive integer e such that 3 ^ e is a factor of 9 ^ 10 ?
Options: a. e = 5, b. e = 9, c. e = 10, d. e = 20, e. 30

SOLUTION: d

PROBLEM: Problem: for any integer n greater than 1, n * denotes the product of all the integers from 1 to n, inclusive. how many prime numbers are there between 6 * + 2 and 6 * + 6, inclusive ?
Options: a. none, b. one, c. two, d. three, e. four

SOLUTION:
a