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: 6 men and 8 women can complete a work in 10 days. 26 men and 48 women can finish the same work in 2 days. 15 men and 20 women can do the same work in - days.
Options: a. 4 days, b. 6 days, c. 2 days, d. 8 days, e. 10 days

Ex Output:
a

Ex Input:
Problem: what least number must be subtracted from 13294 so that the remainder is exactly divisible by 97 ?
Options: a. 3, b. 5, c. 7, d. 9, e. 10

Ex Output:
b

Ex Input:
Problem: a can contains a mixture of liquids a and b is the ratio 7: 5. when 18 litres of mixture are drawn off and the can is filled with b, the ratio of a and b becomes 7: 9. how many liter of liquid a was contained by the can initially ?
Options: a. 32, b. 52, c. 62, d. 42, e. 48

Ex Output:
d