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 waitress ' s income consists of her salary and tips. during one week, her tips were 3 / 4 of her salary. what fraction of her income for the week came from tips ?
Options: a. 1 / 9, b. 1 / 6, c. 3 / 7, d. 4 / 9, e. 5 / 9
[A]: c


[Q]: Problem: in a group of 100 people, 90 have an age of more 30 years, and the others have an age of less than 20 years. if a person is selected at random from this group, what is the probability the person ' s age is less than 20 ?
Options: a. 0.1, b. 0.55, c. 0.65, d. 0.75, e. 0.85
[A]: a


[Q]: Problem: a certain article of clothing was discounted during a special sale to 3 / 4 of its original retail price. when the clothing did n ' t sell, it was discounted even further to 1 / 3 of its original retail price during a second sale. by what percent did the price of this article of clothing decrease from the first sale to the second sale ?
Options: a. 50 %, b. 33.33 %, c. 25 %, d. 55.55 %, e. 12.5 %
[A]:
d