Multiply and Then, If Possible, Simplify by Factoring $\sqrt{x^{8} y^{2}} \sqrt{x y^{7}}$

Multiple Choice

Multiply and then, if possible, simplify by factoring.
- $\sqrt{x^{8} y^{2}} \sqrt{x y^{7}}$

A) $x^{4} y^{4} \sqrt{x y}$
B) $x^{8} y^{8} \sqrt{x y}$
C) $\sqrt{x^{9} y^{9}}$
D) $x^{4} \sqrt{x y^{9}}$