Which of the following is a polynomial?O A. A + x 4 + 16+ 2C.(x - 2)(x4 +3)D. x2 - 1

The Plug, this is the solution:
A. x^4 + x^-4 - 16 is the correct answer because it can be written in the form:
f (x) = AnX^n + .... + A2X² + AX + A
The three additional options can't be written in this form, therefore they're not polynomials.