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Simplify.
[tex]8\sqrt{63x^{14} 14y^{9}[/tex]
Assume x and y are nonnegative.

A: [tex]24x^{7}y^{4}\sqrt{7y}[/tex]
B: [tex]3x^{7}y^{4}\sqrt{7y}[/tex]
C: [tex]24x^{5}y^{4}\sqrt{7x^{2}y}[/tex]
D: [tex]24x^{7}y^{3}\sqrt{7}[/tex]