Which polynomial is a difference of two squares?

x2 + 25

x2 - 25

x2 - 10

x2 + 10

Difference of two numbers means one number subtracted from the other number. x^2 is the square of x. 25 = 5^2, and 5^2 is the square of 5. So this is the difference of x^2 and 5^2, the difference of two squares.

x^2 - 25 = (x-5) (x+5)

answer = x^2-25.