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: find the maximum value of the function f ( x ) = x − 5 if x is a number between - 5 and 13.
Options: a. 6, b. 7, c. 8, d. 9, e. none
c

Problem: mary works in a restaurant a maximum of 70 hours. for the first 20 hours, she is paid $ 8 per hour. for each overtime hour, she is paid at a rate which is 25 % higher than her regular rate. how much mary can earn in a week ?
Options: a. 600, b. 620, c. 660, d. 320, e. 400
c

Problem: 0.002 x 0.4 = ?
Options: a. 8.0, b. 0.008, c. 0.08, d. 0.8, e. 0.0008

e