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: raman mixed 48 kg of butter at rs. 150 per kg with 36 kg butter at the rate of rs. 125 per kg. at what price per kg should he sell the mixture to make a profit of 40 % in the transaction ?
Options: a. 129, b. 287, c. 195, d. 188, e. 112

Ex Output:
c


Ex Input:
Problem: an assembly line produces 15 cogs per hour until an initial order of 60 cogs is completed. the speed of the assembly line is then immediately increased so that it can produce 60 cogs per hour until another 60 cogs are produced. what is the overall average output, in cogs per hour, for the assembly line during this whole time ?
Options: a. 20, b. 22, c. 24, d. 26, e. 28

Ex Output:
c


Ex Input:
Problem: the diameter of the driving wheel of a bus in 140 cm. how many revolutions per minute must the wheel make in order to keep a speed of 14 kmph ?
Options: a. 53.03, b. 50.01, c. 23.23, d. 24.23, e. 41.23

Ex Output:

a