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: if julie rows 32 km upstream and 72 km down steam taking 4 hours each, then the speed of the stream
Options: a. 1.5 kmph, b. 0.5 kmph, c. 0.4 kmph, d. 1.6 kmph, e. 2.5 kmph
Example Output: b

Example Input: Problem: 2.205 divided by 0.3 gives
Options: a. 7.35, b. 6.25, c. 8.15, d. 6.95, e. none of these
Example Output: a

Example Input: Problem: irin, ingrid and nell bake chocolate chip cookies in the ratio of 9.18: 5.17: 2.05. if altogether they baked a batch of 150 cookies, what percent of the cookies did nell bake ?
Options: a. 0.125 %, b. 1.25 %, c. 12.6 %, d. 125 %, e. 0.152 %
Example Output:
c