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: ( ( - 1.9 ) ( 0.6 ) – ( 2.6 ) ( 1.2 ) ) / 2.0 = ?
Options: a. - 0.71, b. - 2.13, c. 1.07, d. 1.71, e. 2.71
Example Output: b

Example Input: Problem: sheila works 8 hours per day on monday, wednesday and friday, and 6 hours per day on tuesday and thursday. she does not work on saturday and sunday. she earns $ 360 per week. how much does she earn in dollars per hour ?
Options: a. 11, b. 10, c. 9, d. 8, e. 7
Example Output: b

Example Input: Problem: last year department store x had a sales total for december that was 6 times the average ( arithmetic mean ) of the monthly sales totals for january through november. the sales total for december was what fraction of the sales total for the year ?
Options: a. 6 / 17, b. 4 / 15, c. 1 / 3, d. 4 / 11, e. 4 / 5
Example Output:
a