pany uses MSTP within their switched LAN.  What is the main purpose of Multiple Instance  Spanning Tree Protocol （MSTP）？（）

• A、 To enhance Spanning Tree troubleshooting on multilayer switches
• B、 To reduce the total number of spanning tree instances necessary for a particular topology 
• C、 To provide faster convergence when topology changes occur in a switched network
• D、 To provide protection for STP when a link is unidirectional and BPDUs are being sent but not  received
• E、 None of the other alternatives apply