Which two values are used by Spanning Tree Protocol to elect a root bridge?

Which two values are used by Spanning Tree Protocol to elect a root bridge? (Choose two.)

A.
bridge priority

B.
IP address

C.
MAC address

D.
IOS version

E.
amount of RAM

F.
speed of the links

Explanation:
Two values are compared to elect a root bridge in STP: bridge priority and MAC address.
Switch having lowest bridge ID will become the root bridge. The bridge ID is how STP keeps track of all the switches in the network. It is determined by a combination of the bridae priority (32.768 bv default on all Cisco switches) and the base MAC address. The bridae with the lowest bridae ID becomes the root bridae in the network.