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.

Input: Consider Input: Problem: four bells commence tolling together and toll at intervals of 2, 4, 6, 8 seconds respectively. in 18 minutes, how many times do they toll together ?
Options: a. 43, b. 44, c. 45, d. 46, e. 47

Output: c


Input: Consider Input: Problem: water is leaking out from a cylinder container at the rate of 0.31 m ^ 3 per minute. after 10 minutes, the water level decreases 1 / 9 meters. what is value of the radius in meters ?
Options: a. 2, b. 3, c. 4, d. 6, e. 9

Output: b


Input: Consider Input: Problem: an article is sold at a certain price. by selling it at 2 / 3 of that price one loses 10 %. find the gain percent at original price ?
Options: a. 25 %, b. 20 %, c. 35 %, d. 40 %, e. 50 %


Output: c