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 is the smallest integer that is multiple of 5, 711
Options: a. a. 70, b. b. 35, c. c. 385, d. d. 280, e. e. 140

Ex Output:
c


Ex Input:
Problem: if a sum of money doubles itself in 20 years at simple interest, the ratepercent per annum is
Options: a. 12, b. 12.5, c. 13, d. 5, e. 14

Ex Output:
d


Ex Input:
Problem: a rectangular grassy plot 110 m. by 65 m has a gravel path 2.5 m wide all round it on the inside. find the cost of gravelling the path at 70 paise per sq. metre
Options: a. s 595, b. s 780, c. s 880, d. s 480, e. s 980

Ex Output:

a