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: what is the units digit of 26 ! + 50 ! + 4 ! + 4 ! ?
Options: a. 8, b. 6, c. 4, d. 2, e. 0
[EX A]: a

[EX Q]: Problem: for the past n days, the average ( arithmetic mean ) daily production at a company was 50 units. if today ' s production of 110 units raises the average to 55 units per day, what is the value of n ?
Options: a. 9, b. 11, c. 13, d. 15, e. 17
[EX A]: b

[EX Q]: Problem: in a 100 m race a beats b by 25 m b beats c by 4 then a beats c by
Options: a. 24 m, b. 25 m, c. 26 m, d. 27 m, e. 28 m
[EX A]:
e