Let $\mathrm { P } ( \mathrm { x } )$ be a second-degree polynomial and $\mathrm { Q } ( \mathrm { x } ) = \mathrm { k }$ be a constant polynomial such that
$$\begin{aligned}
& P ( x ) + Q ( x ) = 2 x ^ { 2 } + 3 \\
& P ( Q ( x ) ) = 9
\end{aligned}$$
Accordingly, what is the sum of the values that k can take?\\
A) $\frac { 1 } { 2 }$\\
B) $\frac { 1 } { 3 }$\\
C) $\frac { 2 } { 3 }$\\
D) $\frac { 1 } { 4 }$\\
E) $\frac { 3 } { 4 }$