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: 108 ã — 108 + 92 ã — 92 = ?
Options: a. 20120, b. 11500, c. 20128, d. 20660, e. 20228
[EX A]: c

[EX Q]: Problem: a man sitting in a train which is traveling at 36 kmph observes that a goods train, traveling in opposite direction, takes 10 seconds to pass him. if the goods train is 240 m long, find its speed
Options: a. 50 kmph, b. 56 kmph, c. 58 kmph, d. 62 kmph, e. 72 kmph
[EX A]: a

[EX Q]: Problem: a sells a bicycle to b and makes a profit of 25 %. b sells the same bicycle to c at a profit of 25 %. if the final s. p. of the bicycle was rs. 225, find out the cost price of the bicycle for a.
Options: a. 237, b. 126, c. 971, d. 611, e. 144
[EX A]:
e