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.

Example 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
Example Output: b

Example Input: Problem: what is the rate percent when the simple interest on rs. 810 amount to rs. 155 in 4 years ?
Options: a. 4.78, b. 4.68, c. 4.58, d. 4.48, e. 4.38
Example Output: a

Example Input: Problem: you need to unlock a secret code using following clues, can you ? here you have the clues: clue - 1: 0 7 9 ( one of the numbers is correct and is placed in its correct position ) clue - 2: 0 3 2 ( nothing is correct ) clue - 3: 1 0 8 ( two numbers are correct but not placed at its correct position. ) clue - 4: 9 2 6 ( one number is correct but not placed at its correct position. ) clue - 5: 6 7 8 ( one number is correct but not placed at its correct position. )
Options: a. 819, b. 918, c. 198, d. 189, e. 891
Example Output:
a