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.

[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
[A]: d


[Q]: Problem: a train traveled the first d miles of its journey it an average speed of 50 miles per hour, the next d miles of its journey at an average speed of y miles per hour, and the final d miles of its journey at an average speed of 160 miles per hour. if the train ’ s average speed over the total distance was 96 miles per hour, what is the value of y ?
Options: a. 68, b. 84, c. 90, d. 120, e. 160
[A]: e


[Q]: Problem: a merchant gets a 5 % discount on each meter of fabric he buys after the first 2,000 meters and a 7 % discount on every meter after the next 1,500 meters. the price, before discount, of one meter of fabric is $ 2, what is the total amount of money the merchant spends on 6,500 meters of fabric ?
Options: a. $ 11,320, b. $ 12,430, c. $ 13,540, d. $ 14,650, e. $ 15,760
[A]:
b