The Solution of the System of Differential Equations $\begin{array} { l } \frac { d x } { d t } = 3 x - y \\\frac { d y } { d t } = 9 x - 3 y\end{array}$

The solution of the system of differential equations $\begin{array} { l } \frac { d x } { d t } = 3 x - y \\\frac { d y } { d t } = 9 x - 3 y\end{array}$ is

A) $x = \left( c _ { 1 } + 3 c _ { 1 } t + 3 c _ { 2 } \right) / 9 , y = c _ { 1 } t + c _ { 2 }$
B) $x = \left( 3 c _ { 1 } t + 3 c _ { 2 } \right) / 9 , y = c _ { 1 } t + c _ { 2 }$
C) $x = \left( c _ { 1 } + 3 c _ { 1 } t \right) / 9 , y = c _ { 1 } t + c _ { 2 }$
D) $x = \left( c _ { 1 } + 3 c _ { 1 } t + 3 c _ { 2 } \right) , y = c _ { 1 } t + c _ { 2 }$
E) $x = \left( c _ { 1 } - 3 c _ { 1 } t + 3 c _ { 2 } \right) / 9 , y = c _ { 1 } t + c _ { 2 }$