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: a sum of money at simple interest amounts to $ 645 in 3 years and to $ 690 in 4 years. the sum is :
Options: a. $ 153, b. $ 510, c. $ 598, d. $ 549, e. $ 675
Example Output: b

Example Input: Problem: the denominator of a fraction is 7 greater than the numerator. if the numerator and the denominator are increased by 4, the resulting fraction is equal to 5 â  „ 6. what is the value of the original fraction ?
Options: a. 23 / 30, b. 25 / 32, c. 31 / 38, d. 37 / 44, e. 47 / 54
Example Output: c

Example Input: Problem: ake can dig a well in 16 days. paul can dig the same well in 24 days. jake, paul and hari together dig the well in 8 days. hari alone can dig the well in
Options: a. 48, b. 39, c. 37, d. 27, e. 29
Example Output:
a