Solve the System by the Method of Substitution $$\left\{ \begin{array} { l } y = - 3 x \\y = x ^ { 3 } + 3 x ^ { 2 } + 3 x\end{array} \right.$$

Multiple Choice

Solve the system by the method of substitution.
$$\left\{ \begin{array} { l } y = - 3 x \\y = x ^ { 3 } + 3 x ^ { 2 } + 3 x\end{array} \right.$$

A) $( 0,6 )$
B) $( 0,0 )$
C) $( 6,3 ) , ( - 6 , - 3 )$
D) $( 6,3 )$
E) no real solution