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: mr. loyd wants to fence his square shaped land of 120 sqft each side. if a pole is laid every 12 ft how many poles do he need ?
Options: a. 20, b. 30, c. 40, d. 50, e. 60

Ex Output:
c


Ex Input:
Problem: a monkey ascends a greased pole 10 meters high. he ascends 2 meters in the first minute and then slips down 1 meter in the alternate minute. if this pattern continues until he climbs the pole, in how many minutes would he reach at the top of the pole ?
Options: a. 10 th minute, b. 21 st minute, c. 17 th minute, d. 22 nd minute, e. 13 th minute

Ex Output:
c


Ex Input:
Problem: joe invested a certain sum of money in a simple interest bond whose value grew to $ 310 at the end of 3 years and to $ 410 at the end of another 5 years. what was the rate of interest in which he invested his sum ?
Options: a. 6 %, b. 7 %, c. 8 %, d. 9 %, e. 10 %

Ex Output:

c