What would be used to combine multiple switches into a single management platform?

You received an alert from your monitoring system that the master Routing Engine (RE) on an EX4300 switch in a virtual chassis has hardware issues and might need to be replaced. Because the switch already had graceful Routing Engine switchover (GRES) enabled and configured, you must perform a manual switchover to the backup RE to avoid disruption.
Which command would be used to perform the manual RE switchover?

Exhibit.

In the exhibit, each IP subnet in the network is associated with a unique VLAN ID.
Which action will ensure that Host C will communicate with Host A and Host B?

Which two situations would cause dynamic ARP inspection to drop traffic? (Choose two.)

What are three RSTP port states? (Choose three.)