In reference to the network topology diagram shown in the exhibit, which statement is true?

A.
The network is using a two-layer hub-and-spoke hierarchical design.

B.
The network is using a two-layer full-mesh hierarchical design.

C.
Routers R1,R2,R3,R4,R5 and R6 are the access layer routers.

D.
To improve security, packet filtering that uses ACLs at Routers A and B must be implemented.

E.
To improve scalability, route summarization at Routers R1,R2,R3,R4,R5,R6 must be
performed.

F.
Routers A and B are the distribution layer routers.