Solve the Equation $21 ( z - 9 ) - z ( z - 9 ) = 0$

Multiple Choice

Solve the equation. $21 ( z - 9 ) - z ( z - 9 ) = 0$

A) $\{ - 21 , - 9 \}$
B) $\{ 21,9 \}$
C) $\{ 21 , - 9 \}$
D) $\{ 21 \}$
E) $\{ - 21,9 \}$