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: if a / b = 1 / 3, b / c = 2, c / d = 1 / 2, d / e = 3 and e / f = 1 / 10, then what is the value of abc / def ?
Options: a. 27 / 4, b. 27 / 8, c. 3 / 4, d. 3 / 20, e. 1 / 4
[EX A]: d

[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: what is the perimeter, in meters, of a rectangular garden 16 meters wide that has the same area as a rectangular playground 16 meters long and 12 meters wide ?
Options: a. 48, b. 56, c. 60, d. 56, e. 192
[EX A]:
d