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.

[EX Q]: Problem: if p ( a. = 5 / 7 and p ( b. = 2 / 5, find p ( a n b. if a and b are independent events.
Options: a. 7 / 25, b. 3 / 25, c. 8 / 25, d. 2 / 7, e. 3 / 17
[EX A]: d

[EX Q]: Problem: the diagonal of a rectangle is √ 41 cm and its area is 20 sq. cm. the perimeter of the rectangle must be :
Options: ['a. 18', 'b. 28', 'c. 38', 'd. 48', 'e. 58']
[EX A]: a

[EX Q]: Problem: a river 4 m deep and 40 m wide is flowing at the rate of 4 kmph the amount of water that runs into the sea per minute is ?
Options: a. 10666, b. 11678, c. 12345, d. 10678, e. 19099
[EX A]:
a