An IP router implementing Classless Inter-domain Routing (CIDR) receives a packet with address $128.96.39.10.$
The router's routing table has the following entries:
$$
\begin{array}{|c|c|}
\hline \textbf{Subnet Number} & \textbf{Output Interface Identifier} \\
\hline 128.96 .39 .0 / 25 & \text{R}2 \\
\hline 128.96 .39 .0 / 27 & \text{R}3 \\
\hline 128.96 .40 .0 / 25 & \text{R}4 \\
\hline 192.4 .153 .0 / 26 & \text{R}5 \\
\hline \text{(default)} & \text{R}6 \\
\hline
\end{array}
$$
The identifier of the output interface on which this packet will be forwarded is __________.
- $\text{R}2$
- $\text{R}3$
- $\text{R}4$
- $\text{R}6$
