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: 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
[A]: b


[Q]: Problem: the denominator of a fraction is 7 greater than the numerator. if the numerator and the denominator are increased by 4, the resulting fraction is equal to 5 â  „ 6. what is the value of the original fraction ?
Options: a. 23 / 30, b. 25 / 32, c. 31 / 38, d. 37 / 44, e. 47 / 54
[A]: c


[Q]: Problem: jack and jill are marathon runners. jack can finish a marathon ( 40 km ) in 4.5 hours and jill can run a marathon in 4.0 hours. what is the ratio of their average running speed ? ( jack: jill )
Options: a. 14 / 15, b. 15 / 14, c. 8 / 9, d. 5 / 4, e. can not be determined
[A]:
c