Maximize $P = x y z$ With $x + y = 9$

Multiple Choice

Maximize $P = x y z$ with $x + y = 9$ and $z + y = 9$ , and $\chi$ , $y$ , and $z > 0$ .

A) $P = 105$
B) $P = 102$
C) $P = 108$
D) $P = 324$
E) $P = 9$