Help I am so confused

1.)Which equation does not support the fact that polynomials are closed under multiplication?

−1⋅−1=1

1x⋅x=1

1⋅x=x

13⋅3=1

2.)Multiply and simplify.

x^2⋅x⋅x^5

3.)Multiply and simplify.

(3x+7)8x^2