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.
--------
Question: Problem: in what time will a railway train 50 m long moving at the rate of 36 kmph pass a telegraph post on its way ?
Options: a. 5 sec, b. 4 sec, c. 3 sec, d. 6 sec, e. 1 sec

Answer: a


Question: Problem: what is the area of a regular hexagon with sides 1 in. long ?
Options: a. 1.59 square inch, b. 2.59 square inch, c. 3.59 square inch, d. 4.59 square inch, e. 2.69 square inch

Answer: b


Question: Problem: excluding stoppages, the speed of a train is 60 kmph and including stoppages it is 40 kmph. of how many minutes does the train stop per hour ?
Options: a. 12, b. 14, c. 16, d. 18, e. 20

Answer:
e