Which two statements regarding route reflectors are true? (Choose two)

A.
A non-route reflector capable router cannot be a client.

B.
A hierarchical route reflector design is where a route reflector client is not directly connected to the route reflector.

C.
If a client has IBGP sessions to other clients in the same cluster, those clients will receive unnecessary duplicated BGP updates.

D.
If a client in one cluster has an IBGP session to a route reflector that belongs to different clusters, the clients in the other cluster will receive unnecessary duplicated BGP updates.

Explanation:

If a client has IBGP sessions to route reflectors that belong to different clusters, the BGP update from the client will be forwarded into the full mesh with different cluster-IDs in the cluster-list attribute. When the BGP update enters the mesh it will reach the other route reflector, which will, unnecessarily, accept the route as valid and forward it into its cluster. This, in turn, causes unnecessarly duplication of updates to the clients. If a client has IBGP sessions to other clients in the same cluster, those clients will receive unnecessarly duplications of updates.
Reference: Reference: Configuring BGP on Cisco routers volume1 p.5-19