Answer:
[tex]\huge\boxed{C.\ -x^3-2x-12}[/tex]
Step-by-step explanation:
[tex](x+2)(-x^2+2x-6)\\\\=(x)(-x^2)+(x)(2x)+(x)(-6)+(2)(-x^2)+(2)(2x)+(2)(-6)\\\\=-x^3+2x^2-6x-2x^2+4x-12\\\\\text{combine like terms}\\\\=-x^3+(2x^2-2x^2)+(-6x+4x)-12\\\\=-x^3-2x-12[/tex]
