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: ( ( - 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

Ex Output:
b


Ex Input:
Problem: in a factory, an average of 60 tv ' s are produced per day for the fist 25 days of the months. a few workers fell ill for the next 5 days reducing the daily avg for the month to 58 sets / day. the average production per day for day last 5 days is ?
Options: a. 20, b. 36, c. 48, d. 50, e. 59

Ex Output:
c


Ex Input:
Problem: micheal and adam can do together a piece of work in 20 days. after they have worked together for 15 days micheal stops and adam completes the remaining work in 10 days. in how many days micheal complete the work separately.
Options: a. 40 days, b. 100 days, c. 120 days, d. 110 days, e. 90 days

Ex Output:

a