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.

[Q]: Problem: in one hour, a boat goes 19 km / hr along the stream and 9 km / hr against the stream. the speed of the boat in still water ( in km / hr ) is :
Options: a. 12 kmph, b. 13 kmph, c. 14 kmph, d. 15 kmph, e. 16 kmph
[A]: c


[Q]: Problem: maxwell leaves his home and walks toward brad ' s house. one hour later, brad leaves his home and runs toward maxwell ' s house. if the distance between their homes is 14 kilometers, maxwell ' s walking speed is 4 km / h, and brad ' s running speed is 6 km / h. what is the total time it takes maxwell before he meets up with brad ?
Options: a. 2, b. 4, c. 5, d. 6, e. 8
[A]: a


[Q]: Problem: the smallest value of n, for which n + 3 is not a prime number, is
Options: a. 1, b. 2, c. 6, d. 8, e. 3
[A]:
e