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: on a certain day, orangeade was made by mixing a certain amount of orange juice with an equal amount of water. on the next day, orangeade was made by mixing the same amount of orange juice with twice the amount of water. on both days, all the orangeade that was made was sold. if the revenue from selling the orangeade was the same for both days and if the orangeade was sold at $ 0.30 per glass on the first day, what was the price per glass on the second day ?
Options: a. $ 0.15, b. $ 0.20, c. $ 0.30, d. $ 0.40, e. $ 0.45

Ex Output:
b

Ex Input:
Problem: mrs. evans gave a test to her freshmen economics class, which has 29 students enrolled and 19 of them answered question 1 correctly. if 24 answered question 2 correctly and 5 did not take the test then how many answered both questions correctly ?
Options: a. 3, b. 9, c. 11, d. 17, e. 19

Ex Output:
e

Ex Input:
Problem: if x > 3000, then the value of ( 1.2 x ) / ( 0.5 x - 406 ) is closest to ?
Options: a. 1 / 6, b. 1 / 3, c. 10 / 21, d. 1 / 2, e. 3 / 1

Ex Output:
e