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: walking at 4 / 5 of her normal speed, a worker is 10 minutes later than usual in reaching her office. the usual time ( in minutes ) taken by her to cover the distance between her home and her office is
Options: a. 30, b. 35, c. 40, d. 45, e. 50
[A]: c

[Q]: Problem: if x ^ 2 4 x = 5, then one possible value of x 2 =
Options: a. - 9, b. - 5, c. - 3, d. - 1, e. 5
[A]: c

[Q]: Problem: if p / q = 4 / 5, then the value of 25 / 7 + { ( 2 q - p ) / ( 2 q + p ) } is ?
Options: a. 4, b. 34, c. 1, d. 2, e. 3
[A]:
a