\textbf{186.} The figure below shows part of an electrical circuit. The input power of the battery is how many watts?
\textit{[Figure: Circuit with battery $\varepsilon = 12\,\text{V}$, internal resistance $r = 3\,\Omega$, current $7\,\text{A}$]}
\begin{itemize}
\item[(1)] $12$
\item[(2)] $18$
\item[(3)] $24$
\item[(4)] $36$
\end{itemize}