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 Input:
Problem: a bag contains 10 green and 8 white balls. if two balls are drawn simultaneously, the probability that both are of the same colour is
Options: a. 8 / 15, b. 21 / 44, c. 3 / 5, d. 11 / 15, e. 7 / 15

Ex Output:
b


Ex Input:
Problem: the length of a rectangular floor is more than its breadth by 100 %. if rs. 600 is required to paint the floor at the rate of rs. 3 per sq m, then what would be the length of the floor ?
Options: a. 15.0 m., b. 14.4 m., c. 12.0 m., d. 16.2 m., e. 16.5 m.

Ex Output:
b


Ex Input:
Problem: a student got twice as many sums wrong as he got right. if he attempted 36 sums in all, how many did he solve correctly ?
Options: a. 12, b. 16, c. 18, d. 24, e. 26

Ex Output:

a