Answer:
A. Enable MAC filtering
Step-by-step explanation:
A media access control (MAC) address is a unique identifier for any hardware connected on a network. The MAC address cannot be changed and is specified from the manufacturer of the device through the network card. In this scenario MAC filtering will only allow devices whose MAC addresses are configured in the allowed list of the router to have network access. If DHCP is enabled, only the allowed devices will be assigned IP addresses via DHCP for network access .MAC filtering protects the network from access by unauthorized devices.