Your answer is b
X^3-8= (x-2)(x^2+2x+4)
To check you multiply each term on first expression to the second expression .
(X-2)(x^2+2x+4)
X(x^2)+x(2x)+x(4) +(-2(x^2)-2(2x)-2(4))
Simplify
X^3+2x^2+4x-2x^2-4x-8
Subtract 2x^2 from 2x^2
X^3+4x+0-4x-8
Add x^3 And 0
X^3+4x-4x-8
Subtract x^3-0
X^3-8