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: a hiker walking at a constant rate of 4 kilometers per hour is passed by a cyclist travelling in the same direction along the same path at a constant rate of 24 kilometers per hour. the cyclist stops and waits for the hiker 5 minutes after passing her while the hiker continues to walk at her constant rate. how many minutes must the cyclist wait until the hiker catches up ?
Options: a. 10, b. 15, c. 20, d. 25, e. 30
Example Output: d

Example Input: Problem: if an investor puts $ 700 in a savings account that earns 10 percent annual interest compounded semiannually, how much money will be in the account after one year ?
Options: a. $ 769.75, b. $ 771.75, c. $ 773.75, d. $ 775.75, e. $ 777.75
Example Output: b

Example Input: Problem: a train running at the speed of 60 km / hr crosses a pole in 7 sec. what is the length of the train ?
Options: a. 112.21, b. 27.21, c. 117.66, d. 277, e. 116.66
Example Output:
e