IEEE 802.1w is a Rapid Spanning Tree Protocol （RSTP） that can be seen as an evolution of the 802.1 standard. What are the port roles described by 802.1w？（）

• A、root port，designated port，alternate port，backup port，and disabled
• B、standby port，alternate port，root port，and disabled
• C、standby port，designated port，backup port，and disabled
• D、root port，designated port，alternate port，and standby port