AMC 12 2009b Problem 9

Triangle $ABC$ has vertices $A = (3,0)$, $B = (0,3)$, and $C$, where $C$ is on the line $x + y = 7$. What is the area of $\triangle ABC$?

\textbf{(A)}\ 6 \textbf{(B)}\ 8 \textbf{(C)}\ 10 \textbf{(D)}\ 12 \textbf{(E)}\ 14