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.

Example Input: Problem: the shopkeeper sale, all of the prices of the items sold were different. if the price of a radio sold at the shopkeeper sale was both the 9 th highest price and the 14 th lowest price among the prices of the items sold, how many items were sold at the shopkeeper sale ?
Options: a. 23, b. 22, c. 32, d. 26, e. 17
Example Output: b

Example Input: Problem: cost is expressed by the formula tb ^ 4. if b is doubled, the new cost w is what percent of the original cost ?
Options: a. w = 200, b. w = 600, c. w = 800, d. w = 1600, e. w = 50
Example Output: d

Example Input: Problem: a train 100 m long takes 6 sec to cross a man walking at 5 kmph in a direction opposite to that of the train. find the speed of the train ?
Options: a. 45 kmph, b. 55 kmph, c. 32 kmph, d. 61 kmph, e. 70 kmph
Example Output:
b