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: what is the value of n if the sum of the consecutive odd intergers y from 1 to n equals 169 ?
Options: a. 47, b. 25, c. 37, d. 33, e. 29
[EX A]: b

[EX Q]: Problem: a man can row at 5 kmph in still water. if the velocity of current is 1 kmph and it takes him 2 hour to row to a place and come back, how far is the place ?
Options: a. 2.4 km, b. 4.8 km, c. 3.4 km, d. 4.4 km, e. 5.6 km
[EX A]:
b