The classic Spanning Tree Protocol (802.1D 1998) uses which sequence of variables to determine the best received BPDU?

A.
1) lowest root bridge id, 2) lowest sender bridge id, 3) lowest port id, 4) lowest root path cost

B.
1) lowest root path cost, 2) lowest root bridge id, 3) lowest sender bridge id, 4) lowest sender port id

C.
1) lowest root bridge id, 2) lowest sender bridge id, 3) lowest root path cost 4) lowest sender port id

D.
1) lowest root bridge id, 2) lowest root path cost, 3) lowest sender bridge id, 4) lowest sender port id

Explanation:
The parts of a BPDU are:

* Root BID This is the BID of the current root bridge.
* Path cost to root bridge This determines how far away the root bridge is. For example, if the data has to travel over three 100-Mbps segments to reach the root bridge, then the cost is (19 + 19 + 0) 38.
The segment attached to the root bridge will normally have a path cost of zero.
* Sender BID This is the BID of the switch that sends the BPDU.
* Port ID This is the actual port on the switch that the BPDU was sent from.