Refer to the exhibit:

C-router is to be used as a “router-on-a-stick” to route between the VLANs. All the interfaces have been properly configured and IP routing is operational. The hosts in the VLANs have been configured with the appropriate default gateway. What can be said about this configuration?

A.
These commands need to be added to the configuration:
C-router(config)# router eigrp 123
C-router(config-router)# network 172.19.0.0

B.
No further routing configuration is required.

C.
These commands need to be added to the configuration:
C-router(config)# router ospf 1C-router(config-router)# network 172.19.0.0 0.0.3.255 area 0

D.
These commands need to be added to the configuration:
C-router(config)# router ripC-router(config-router)# network 172.19.0.0

Explanation:
Since all the same router (C-router) is the default gateway for all three VLANs, all traffic destined to a different VLA will be sent to the C-router. The C-router will have knowledge of all three networks since they will appear as directly connected in the routing table. Since the C-router already knows how to get to all three networks, no routing protocols need to be configured.