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: a and b go around a circular track of length 200 m on a cycle at speeds of 36 kmph and 72 kmph. after how much time will they meet for the first time at the starting point ?
Options: a. 120 sec, b. 198 sec, c. 178 sec, d. 20 sec, e. 276 sec

Ex Output:
d


Ex Input:
Problem: a 10000 liter tank, half - full of water is being filled from a pipe with a flow rate of 1 kiloliter every 2 minutes. at the same time, the tank is losing water from two drains at a rate of 1 kiloliter every 4 minutes and every 6 minutes. how many minutes does it take to fill the tank completely ?
Options: a. 8, b. 12, c. 18, d. 24, e. 60

Ex Output:
e


Ex Input:
Problem: jack and christina are standing 240 feet apart on a level surface. their dog, lindy, is standing next to christina. at the same time, they all begin moving toward each other. jack walks in a straight line toward christina at a constant speed of 5 feet per second and christina walks in a straight line toward jack at a constant speed of 3 feet per second. lindy runs at a constant speed of 9 feet per second from christina to jack, back to christina, back to jack, and so forth. what is the total distance, in feet, that lindy has traveled when the three meet at one place ?
Options: a. 180, b. 210, c. 240, d. 270, e. 300

Ex Output:

d


