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: what least number should be added to 1057, so that the sum is completely divisible by 23
Options: a. a. 4, b. b. 1, c. c. 2, d. d. 3, e. e. 5

Ex Output:
b


Ex Input:
Problem: if x is to be chosen at random from the set { 1, 2, 3, 4 } and y is to be chosen at random from the set { 6, 7 }, what is the probability that xy will be even ?
Options: a. 1 / 6, b. 1 / 3, c. 1 / 2, d. 2 / 3, e. 5 / 6

Ex Output:

a