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: at a florist shop on a certain day, all corsages sold for either $ 20 or $ 30. if 10 of the corsages that sold for $ 30 had instead sold for $ 20, then the store ' s revenue from corsages that day would have been reduced by 20 percent. what was the store ' s actual revenue from corsages that day ?
Options: a. $ 200, b. $ 400, c. $ 500, d. $ 800, e. $ 1000
[EX A]: c

[EX Q]: Problem: a fruit - salad mixture consists of apples, peaches, and grapes in the ratio 6: 5: 4, respectively, by weight. if 60 pounds of the mixture is prepared, the mixture includes how many more pounds of apples than grapes ?
Options: a. 15, b. 12, c. 8, d. 6, e. 4
[EX A]: c

[EX Q]: Problem: what is the tens digit of 6 ^ 10 ?
Options: a. 7, b. 3, c. 5, d. 1, e. 9
[EX A]:
a