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: what is the normal price of an article sold at $ 72 after two successive discounts of 10 % and 20 % ?
Options: a. $ 92, b. $ 96, c. $ 100, d. $ 104, e. $ 108
c

Problem: the product x of two prime numbers is between 17 and 60. if one of the prime numbers is greater than 2 but less than 6 and the other is greater than 13 but less than 25, then x =
Options: a. 18, b. 29, c. 37, d. 44, e. 57
e

Problem: what is 78 % of 4 / 5 ?
Options: a. 6.9, b. 69.0, c. 0.6845, d. 0.624, e. 0.69

d