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.

[Q]: Problem: dropbox charges $ 3.10 for first 1 / 5 of a month for 500 gb storage, plus $ 0.40 for each additional 1 / 5 of a month. what would dropbox charge for a data storage of 500 gb for 8 months ?
Options: a. $ 15.60, b. $ 16.00, c. $ 17.80, d. $ 18.70, e. $ 19.10
[A]: d

[Q]: Problem: if two dice are thrown together, the probability of getting an even prime number on the dice is
Options: a. 1 / 36, b. 1 / 18, c. 1 / 13, d. 1 / 9, e. 5 / 36
[A]: a

[Q]: Problem: the price of a jacket is reduced by 25 %. during a special sale the price of the jacket is reduced another 25 %. by approximately what percent must the price of the jacket now be increased in order to restore it to its original amount ?
Options: a. 32.5, b. 77.78, c. 48, d. 65, e. 67.5
[A]:
b