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: a sells a bicycle to b and makes a profit of 50 %. 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. 120
[A]: e


[Q]: Problem: a train 50 m long takes 6 sec to cross a man walking at 5 kmph in a direction opposite to that of the train. find the speed of the train ?
Options: a. 15 kmph, b. 25 kmph, c. 35 kmph, d. 45 kmph, e. 55 kmph
[A]: b


[Q]: Problem: a seller of used cars has 12 cars to sell and each of his clients selected 4 cars that he liked most. if each car was selected exactly thrice, how many clients visited the garage ?
Options: a. 9, b. 10, c. 12, d. 14, e. 16
[A]:
a