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 train, travelling at a speed of 90 kmph, crosses a pole in 4 sec, then the length of train is ?
Options: a. 281, b. 125, c. 288, d. 100, e. 121
[EX A]: d

[EX Q]: Problem: how many positive integer solutions does the equation 8 x + 2 y = 100 have ?
Options: a. 50, b. 84, c. 16, d. 35, e. 14
[EX A]: b

[EX Q]: Problem: the average of 11 numbers is 60. out of 11 numbers the average of first 6 no. is 98, and last 6 numbers is 65 then find 6 th number ?
Options: a. a. 318, b. b. 65, c. c. 58, d. d. 62, e. e. 48
[EX A]:
a