Equivalent expressions SAT question

Choice D is correct. The product of $(x^{-6}{y}^3{z}^5)$ and $(x^4{z}^5+y^8{z}^{-7})$ can be represented by the expression $(x^{-6}{y}^3{z}^5)(x^4{z}^5+y^8{z}^{-7})$. Applying the distributive property to this expression yields $(x^{-6}{y}^3{z}^5)(x^4{z}^5)+(x^{-6}{y}^3{z}^5)(y^8{z}^{-7})$, or $x^{-6}{x}^4{y}^3{z}^5{z}^5+x^{-6}{y}^3{y}^8{z}^5{z}^{-7}$. This expression is equivalent to $x^{-6+4}{y}^3{z}^{5+5}+x^{-6}{y}^{3+8}{z}^{5-7}$, or $x^{-2}{y}^3{z}^{10}+x^{-6}{y}^{11}{z}^{-2}$.

Choice A is incorrect and may result from conceptual or calculation errors.

Choice B is incorrect and may result from conceptual or calculation errors.

Choice C is incorrect and may result from conceptual or calculation errors.