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: what least number should be added to 1057, so that the sum is completely divisible by 23
Options: a. a. 4, b. b. 1, c. c. 2, d. d. 3, e. e. 5

A: b
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Q: Problem: if n is a positive integer and n ^ 2 is divisible by 36, then the largest positive integer that must divide n is
Options: a. 6, b. 12, c. 24, d. 36, e. 48

A: a
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Q: Problem: i had 30 donuts when i left home this morning but only 9 when i came back home. what percentage of the donuts are missing ?
Options: a. 70, b. 65, c. 55, d. 75, e. 60

A:
a
****