Which statement justifies that x2 + 3x − 1 multiplied by 2x2 − 2x + 1 obeys the closure property of multiplication?

(a)the result 2x4 − 6x2 − 1 has a degree of 4.
(b)the result 2x4 − 6x2 − 1 is a trinomial.
(c) the result 2x4 + 4x3 − 7x2 + 5x − 1 has a degree of 4.
(d)the result 2x4 + 4x3 − 7x2 + 5x − 1 is a polynomial.

(x² + 3x - 1)(2x² - 2x + 1)

x²(2x² - 2x + 1) + 3x(2x² -2x + 1) -1(2x² - 2x + 1)
2x^4 - 2x³ + x² + 6x³ - 6x² + 3x - 2x² + 2x - 1
2x^4 - 2x³ + 6x³ + x² - 6x² - 2x² + 3x + 2x - 1
2x^4 + 4x³ - 7x² + 5x - 1

(D)The result 2x4 + 4x3 − 7x2 + 5x − 1 is a polynomial.

The question is kind of confusing. if it's asking how many variations of answers can you give. then do 4^5 for your answer.this would be something like the first question could be a and the 2nd c or first b next c etc. if you can, ask the teacher for a better confirmation of what it's asking. if i'm assuming correctly what it's asking, it's 625 different variations.