Which polynomial is a difference of two squares?
x2 − 16
x2 + 16
x2 − 8
x2 + 8

The difference of two squares is of the form:

(a^2-b^2)

I believe that they might just want you to select

(x^2-16) which factors to (x-4)(x+4)

But there is nothing mathematically incorrect in doing the same for:

(x^2-8) which factors to (x-√8)(x+√8)

Okay so it will be 1123