Answer:
B. Distributive property
Step-by-step explanation:
The distributive property says
[tex](a+b)\cdot c=a\cdot b+b\cdot c[/tex]
You are given the expression
[tex](y^2+y)(x^4+3x^3-2x^3)=y^2(x^4+3x^3-2x^3)+y(x^4+3x^3-2x^3)[/tex]
Denote
[tex]c=x^4+3x^3-2x^3[/tex]
then your expression is
[tex](y^2+y)\cdot c=y^2\cdot c+y\cdot c[/tex]
Here, you can see that distributive property was used.
Now, change c into the [tex]x^4+3x^3-2x^3[/tex] again
[tex](y^2+y)\cdot (x^4+3x^3-2x^3)=y^2\cdot (x^4+3x^3-2x^3)+y\cdot (x^4+3x^3-2x^3)[/tex]
to get the distributive property for the initial expression
