Which statement justifies that 3x2 - 2x - 4 multiplied by 2x2 + x - 3 obeys the closure property of multiplication?

Question

anonymous · Answer

The result 6x4 - 2x2 + 12 has a degree of 4.

 The result 6x4 - 2x2 + 12 is a trinomial.

 The result 6x4 - x3 - 19x2 + 2x + 12 is a polynomial.

 The result 6x4 - x3 - 19x2 + 2x + 12 has a degree of 4.

anonymous · Answer

When I solved it I got 6x^4-2x^2+12 but I don't understand if it has a degree of 4 or if it's a trinomial because they both make sense to me.

anonymous · Answer

I think it's B though.

tkhunny · Answer

WHICH closure property of multiplication?

Is there such a property for DEGREE?  No.
Is there such a property for TRINOMIAL?  No.
Is there such a property for POLYNOMIAL?  Yes.

Well then, there are not to many possible correct answers, are there?