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: a man goes downstream at 10 kmph, and upstream 8 kmph. the speed of the stream is
Options: a. 0 kmph, b. 4 kmph, c. 1 kmph, d. 2.5 kmph, e. 26 kmph

Ex Output:
c


Ex Input:
Problem: the batting average of a particular batsman is 60 runs in 46 innings. if the difference in his highest and lowest score is 140 runs and his average excluding these two innings is 58 runs, find his highest score.
Options: a. 179, b. 367, c. 269, d. 177, e. 174

Ex Output:
e


Ex Input:
Problem: a is half good a work man as b and together they finish a job in 14 days. in how many days working alone b finish the job ?
Options: a. 23, b. 22, c. 21, d. 36, e. 48

Ex Output:

c