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: if the price of a certain computer increased 30 percent from b dollars to 351 dollars, then 2 b =
Options: a. 540, b. 570, c. 619, d. 649, e. 700
[A]: a


[Q]: Problem: a caterer ordered 225 ice - cream bars and 125 sundaes. if the total price was $ 200.00 and the price of each ice - cream bar was $ 0.60, what was the price of each sundae ?
Options: a. $ 0.52, b. $ 0.80, c. $ 1.00, d. $ 1.20, e. $ 1.60
[A]:
a