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 train covers a distance of 100 km in 1 hour. if its speed is decreased by 15 km / hr, the time taken by the car to cover the same distance will be ?
Options: a. 1 hr, b. 1 hr 10 min, c. 50 min, d. 1 hr 30 min, e. 1 hr 45 min

Ex Output:
b


Ex Input:
Problem: dropbox charges $ 3.10 for first 1 / 5 of a month for 500 gb storage, plus $ 0.40 for each additional 1 / 5 of a month. what would dropbox charge for a data storage of 500 gb for 8 months ?
Options: a. $ 15.60, b. $ 16.00, c. $ 17.80, d. $ 18.70, e. $ 19.10

Ex Output:
d


Ex Input:
Problem: the ratio of boys to girls is 6: 4.60 % of the boys and 40 % of girls take lunch in the canteen. what % of class takes lunch ?
Options: a. 51 %, b. 52 %, c. 53 %, d. 54 %, e. 55 %

Ex Output:

b