\textbf{65.} In the circuit below, an ideal ammeter reads $0.25$ A and an ideal voltmeter reads $5$ V. What is $R_1$?
\textit{[Figure: Circuit with $10\,\Omega$ resistor, $R_2$, voltmeter (V), ammeter (A), $R_1$, battery $12\,\text{V}$, internal resistance $r$, and $6\,\Omega$ resistor]}
\begin{itemize}
\item[(1)] $12$
\item[(2)] $16$
\item[(3)] $18$
\item[(4)] $24$
\end{itemize}