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 y exceeds x by 25 %, then x is less than y by ?
Options: a. 28 %, b. 21 %, c. 20 %, d. 30 %, e. 29 %
[EX A]: c

[EX Q]: Problem: ms. harris invested in fund x and fund b. the total amount she invested, in both funds combined, was $ 100000. in one year, fund x paid 23 % and fund b paid 17 %. the interest earned in fund b was exactly $ 200 greater than the interest earned in fund x. how much did ms. morris invest in fund x ?
Options: a. $ 32000, b. $ 36000, c. $ 40000, d. $ 42000, e. $ 45,000
[EX A]: d

[EX Q]: Problem: if the population of a certain country increases at the rate of one person every 15 seconds, by how many persons does the population increase in 25 minutes ?
Options: a. 80, b. 100, c. 150, d. 240, e. 300
[EX A]:
b