Task: Question Answering
Input (English): Question: If two of the four expressions x+y, x+5y, x-y, 5x+y are chosen at random, what is the probability that their product will be of the form of x^2 - (by)^2, where b is an integer?

 Option A: 1/2

 Option B: 1/3

 Option C: 1/4

 Option D: 1/5

 Option E: 1/6
Output (English): Option E