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: 11 is subtracted from 40 % of a number and results is 23. what is the number ?
Options: a. 160, b. 92, c. 88, d. 85, e. 34
[EX A]: d

[EX Q]: Problem: 54671 - 14456 - 31466 = ?
Options: a. 2449, b. 5449, c. 8749, d. 8449, e. 6468
[EX A]: c

[EX Q]: Problem: during the last 4 years, a large truck company purchased diesel at rates of $ 1.2, $ 1.3, $ 1.8 and $ 2.1 per gallon. what was the mean cost of diesel over the 4 - year period if the company spends the same amount of dollars on diesel each year ?
Options: a. $ 2.5, b. $ 2.55, c. $ 1.52, d. $ 3.25, e. $ 3.0
[EX A]:
c