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: the sum of all the integers a such that - 26 < a < 24 is
Options: a. 0, b. - 2, c. - 25, d. - 49, e. - 51
[EX A]: d

[EX Q]: Problem: an error 1 % in excess is made while measuring the side of a square. the percentage of error in the calculated area of the square is :
Options: a. 2.01, b. 30.1, c. 3.01, d. 25.01, e. 4.05
[EX A]: a

[EX Q]: Problem: two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. the ratio of their speeds is :
Options: a. 3 / 7, b. 3 / 2., c. 3 / 88, d. 3 / 8., e. 2 / 2.
[EX A]:
b