How is the bridge ID calculated for PVST+?

A. The bridge ID is a 4-byte bridge priority, a 12-byte sys-id-ext, and 6 byte MAC address.
B. The bridge ID is a 4-byte bridge priority and sys-id-ext and 6-byte MAC address.
C. The bridge ID is a 4-bit bridge priority, 12-bit sys-id-ext, and 6-byte MAC address.
D. The bridge ID is a 4-bit bridge priority, 12-bit sys-id-ext, and an 8-byte IP address.

C. The PVST+ bridge ID comprises a 4-bit bridge priority calculated in blocks of 4096, a 12-bit sys-ext-id that is the VLAN ID for the segment, and a 6-byte MAC address for the switch.