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: if the sum of 5 consecutive even positive integers is a, then the sum of the next 5 even consecutive integers in terms of a is :
Options: a. a + 5, b. a + 10, c. a + 25, d. a + 50, e. 2 a + 5
[A]: d

[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']
[A]: a

[Q]: Problem: a man can swim in still water at 3 km / h, but takes twice as long to swim upstream than downstream. the speed of the stream is ?
Options: a. 1.7, b. 1.4, c. 1.1, d. 1.5, e. 1
[A]:
e