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: a bag contains 21 toys numbered 1 to 21. a toy is drawn and then another toy is drawn without replacement. find the probability that both toys will show even numbers.
Options: a. 5 / 21, b. 9 / 42, c. 6 / 22, d. 4 / 21, e. 3 / 21
[A]: b


[Q]: Problem: the mean proportional between 4 and 16 is ?
Options: a. 12, b. 13, c. 14, d. 15, e. 16
[A]: e


[Q]: Problem: 6 men and 8 women can complete a work in 10 days. 26 men and 48 women can finish the same work in 2 days. 15 men and 20 women can do the same work in - days.
Options: a. 4 days, b. 6 days, c. 2 days, d. 8 days, e. 10 days
[A]:
a