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: what will be the compound interest on a sum of rs. 20,000 after 3 years at the rate of 12 % p. a. ?
Options: a. rs. 8098.56, b. rs. 9720, c. rs. 10123.20, d. rs. 10483.20, e. none

Ex Output:
a


Ex Input:
Problem: vehicle x is 22 miles ahead of vehicle y, which is traveling the same direction along the same route as vehicle x. if vehicle x is traveling at an average speed of 36 miles per hour and vehicle y is traveling at an average speed of 45 miles per hour, how long will it take vehicle y to overtake and drive 23 miles ahead of vehicle x ?
Options: a. 5 hours, b. 7 hours 20 minutes, c. 4 hours, d. 3 hours 45 minutes, e. 2 hours 30 minutes

Ex Output:
a


Ex Input:
Problem: the h. c. f. of two numbers is 20 and the other two factors of their l. c. m. are 13 and 14. the larger of the two numbers is :
Options: a. 276, b. 280, c. 322, d. 345, e. 354

Ex Output:

b