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: the smallest number which when diminished by 2, is divisible by 12, 16, 18, 21 and 28 is
Options: a. 1008, b. 1010, c. 1022, d. 1032, e. 1043
Example Output: b

Example Input: Problem: the number of the members of a club is more than 50 and less than 80. when 4 people sit at a table, other people exactly divided to 8 - people groups ( 8 people sit at a table. or 7 - people groups ( 7 people sit at a table.. if the members are divided to 9 - people groups, how many people will be left ?
Options: a. 0, b. 2, c. 4, d. 6, e. 8
Example Output: d

Example Input: Problem: a farmer has enough food to feed her 1000 cows for 50 days. after 10 days some of the cows run away and the food was now enough for the same period of 50 days as before. how many cows ran away ?
Options: a. 300, b. 200, c. 500, d. 400, e. 250
Example Output:
b