Final answer:
The path cost determines which port on a non-root bridge will become the root port in an STP network.
Therefore, the correct answer is: option D) The path cost.
Step-by-step explanation:
In an STP (Spanning Tree Protocol) network, the port on a non-root bridge that becomes the root port is determined based on the path cost. The path cost is calculated by adding up the cost of each link between the non-root bridge and the root bridge.
The lowest path cost determines which port on the non-root bridge will become the root port. The lower the cost, the more favorable the port is in terms of becoming the root port.
It is used for creating a loop-free topology. Types of STP are Rapid Spanning Tree Protocol, virtual LAN, Per VLAN spanning tree, Per VLAN Rapid spanning tree, Multiple Spanning Tree Protocol, etc.
For example, if a non-root bridge has multiple ports connecting to the root bridge, the port with the lowest path cost will be chosen as the root port.