Correct answer should be B
B. **Reduce the number of equipment**

Router-on-a-stick is a method of inter-VLAN routing that uses a single physical interface on a router, which is configured with multiple sub-interfaces. Each sub-interface is associated with a specific VLAN, allowing the router to route traffic between the VLANs using one physical interface. This approach reduces the number of physical interfaces and potentially the number of routers needed, thus reducing equipment requirements.

Here's why the other options are not applicable:

- **A. Reduce the use of IP addresses**: The router-on-a-stick approach does not reduce the number of IP addresses used. Each VLAN still requires its own subnet and corresponding IP addresses.

- **C. Reduce the number of chain connections**: This option is not directly applicable as the router-on-a-stick approach involves configuring trunk connections rather than affecting chain connections.

- **D. Reduce routing table entries**: The router-on-a-stick method does not necessarily reduce routing table entries. Each VLAN requires its own routing entries....