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: the overall age of x and y is 19 year greater than the overall age of y and z. z is how many decades younger that x ?
Options: a. 11, b. 15, c. 12, d. 19, e. 20

Ex Output:
d


Ex Input:
Problem: a man traveled from the village to the post - office at the rate of 25 kmph and walked back at the rate of 4 kmph. if the whole journey took 5 hours 48 minutes, find the distance of the post - office from the village ?
Options: a. 70 m, b. 80 km, c. 20 km, d. 10 km, e. 73 km

Ex Output:
c


Ex Input:
Problem: in digging a pond 20 m * 10 m * 5 m the volumes of the soil extracted will be ?
Options: a. 100 cu. m, b. 1000 cu. m, c. 10000 cu. m, d. 2000 cu. m, e. 4000 cu. m

Ex Output:

b