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: find the simple interest on rs. 72,000 at 16 2 / 3 % per year for 9 months.
Options: a. 7500, b. 6500, c. 9000, d. 9500, e. none of them

Ex Output:
c


Ex Input:
Problem: the average of first 10 natural numbers is ?
Options: a. 5.6, b. 5.5, c. 5.1, d. 5.8, e. 5.2

Ex Output:
b


Ex Input:
Problem: ravi and kavi start a business by investing â ‚ ¹ 2000 and â ‚ ¹ 72000, respectively. find the ratio of their profits at the end of year.
Options: a. 2: 36, b. 5: 36, c. 7: 36, d. 1: 36, e. 3: 36

Ex Output:

d