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.

Problem: a 11 % stock yields 8 %. the market value of the stock is :
Options: a. rs. 72, b. rs. 137.50, c. rs. 112.50, d. rs. 116.50, e. none of these
b

Problem: the speed of a boat in still water is 15 km / hr and the rate of current is 3 km / hr. the distance travelled downstream in 24 minutes is
Options: a. 17.2 km, b. 7.2 km, c. 7.6 km, d. 17.6 km, e. 27.2 km
b

Problem: a certain high school has 500 students. of these students, 20 are taking music, 20 are taking art, and 10 are taking both music and art. how many students are taking neither music nor art ?
Options: a. 430, b. 440, c. 450, d. 460, e. 470

e