Which of the following shows that polynomials are closed under addition when two polynomials 4x + 6 and 2x2 − 8x − 4 are added? 2x2 − 4x + 2; will be a polynomial 2x2 − 4x + 2; may or may not be a polynomial 2x2 − 12x − 10; will be a polynomial 2x2 − 12x − 10; may or may not be a polynomial