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 Q]: 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
[EX A]: c

[EX Q]: Problem: 18.05 ã — 0.001 = ?
Options: a. 0.1805, b. 0.01805, c. 1.805, d. 0.001805, e. none of these
[EX A]: b

[EX Q]: Problem: a fair price shopkeeper takes 10 % profit on his goods. he lost 70 % goods during theft. his loss percent is :
Options: a. 72 %, b. 42 %, c. 32 %, d. 67 %, e. 22 %
[EX A]:
d