Let $a$ and $b$ be real numbers. It is known that the polynomial
$$f ( x ) = x ^ { 3 } + a x ^ { 2 } + b x + 1$$
is
\begin{itemize}
\item increasing on the interval $( - \infty , 1 )$,
\item decreasing on the interval $( 1,5 )$,
\item increasing on the interval $( 5 , \infty )$.
\end{itemize}
Accordingly, what is $f ( 2 )$?\\
A) 0\\
B) 3\\
C) 6\\
D) 9\\
E) 12