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.

Input: Consider Input: Problem: if a and b are positive real numbers, and a ^ 3 + b ^ 3 = 25, then the greatest possible value of a is between :
Options: a. 0 and 3, b. 3 and 4, c. 4 and 5, d. 5 and 7, e. 7 and 9

Output: a

Input: Consider Input: Problem: a store reported total sales of $ 460 million for february of this year. if the total sales for the same month last year was $ 320 million, approximately what was the percent increase in sales ?
Options: a. 2 %, b. 17 %, c. 44 %, d. 65 %, e. 83 %

Output: c

Input: Consider Input: Problem: a can complete a project in 20 days and b can complete the same project in 40 days. if a and b start working on the project together and a quits 10 days before the project is completed, in how many days will the project be completed ?
Options: a. 18 days, b. 20 days, c. 26.67 days, d. 16 days, e. 12 days
Output: b