What is the purpose of a chassis cluster?

A.
Chassis clusters are used to aggregate routes.

B.
Chassis clusters are used to create aggregate interfaces.

C.
Chassis clusters are used to group two chassis into one logical chassis.

D.
Chassis clusters are used to group all interfaces into one cluster interface.

Explanation:
The Junos OS achieves high availability on Junos security platforms using chassis clustering. Chassis clustering
provides network node redundancy by grouping two like devices into a cluster. The two nodes back each other
up with one node acting as the primary and the other as the secondary node, ensuring the stateful failover of
processes and services in the event of system or hardware failure. A control link between services processing
cards (SPCs) or revenue ports and an Ethernet data link between revenue ports connect two like devices. Junos
security platforms must be the same model, and all SPCs, network processing cards (NPCs), and input/output
cards (IOCs) on high-end platforms must have the same slot placement and hardware revision.
The chassis clustering feature in the Junos OS is built on the high availability methodology of Juniper Networks
M Series and T Series platforms and the TX Matrix platform, including multichassis clustering, active-passive
Routing Engines (REs) , active-active Packet Forwarding Engines (PFEs), and graceful RE switchover capability.