Which two options are disadvantages of a commingled dual-tier WAN rate-based Ethernet circuit?

Which two options are disadvantages of a commingled dual-tier WAN rate-based Ethernet circuit?
(Choose two.)

A.
It requires the maintenance of separate chassis.

B.
It has limited scalability.

C.
It requires additional CPU resources at the subscriber end.

D.
It is more difficult to secure.

E.
It can increase the likelihood of packet drops.