You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

Q: Question: A box contains 9 pairs of shoes (18 shoes in total). If two shoes are selected at random, what it is the probability that they are matching shoes?

 Option A: 1/190

 Option B: 1/17

 Option C: 1/19

 Option D: 1/10

 Option E: 1/9

A: Option B
****
Q: Question: If x is positive and y is negative, which of the following must be true?

 Option A: The product of x and y is positive

 Option B: The sum of x and y is positive

 Option C: The sum of x and y is negative

 Option D: The difference of x and y is positive

 Option E: The sum of x^2 and y^2 is positive

A: Option E
****
Q: Question: If n is a positive integer and n^2 is divisible by 264, then the largest positive integer that must divide n is

 Option A: 6

 Option B: 12

 Option C: 24

 Option D: 36

 Option E: 48

A:
Option E
****