What is the role of the root port on a nonroot switch in STP?

The root port on a nonroot switch is the port that provides the best, lowest-cost path to the root bridge. Every nonroot switch in a Spanning Tree Protocol (STP) topology will have exactly one root port. This port is responsible for forwarding traffic to and from the root bridge, ensuring connectivity within the spanning tree. The other options are incorrect because: A root port does not replace a designated port; they serve different functions. A designated port is the best port on a segment, while a root port is the best port on a nonroot switch toward the root bridge. A root port does not replace itself when it fails; rather, STP recalculates and selects a new root port if an alternative path exists. Root ports are active and forwarding traffic; they are not administratively disabled.