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 man can row upstream at 25 kmph and downstream at 55 kmph, and then find the speed of the man in still water ?
Options: a. 65, b. 40, c. 30, d. 78, e. 38

A: b
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Q: Problem: if a ' s height is 40 % less than that of b, how much percent b ' s height is more than that of a ?
Options: a. 66.66 %, b. 66.68 %, c. 66.766 %, d. 86.66 %, e. 66.65 %

A: a
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Q: Problem: the profits of qrs company rose 20 % from march to april, then dropped 20 % from april to may, then rose 50 % from may to june. what was the percent increase for the whole quarter, from march to june ?
Options: a. 15 %, b. 32 %, c. 44 %, d. 62 %, e. 80 %

A:
c
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