Switch R1 has been configured with DTP using the desirable option.  Which statement describes  Dynamic Trunking Protocol （DTP） desirable mode？（）

• A、 The interface actively attempts to convert the link to a trunk link.
• B、 The interface is put into permanent trunking mode but prevented from generating DTP frames.  
• C、 The interface is put into permanent trunking mode and negotiates to convert the link into a trunk  link.
• D、 The interface is put into a passive mode， waiting to convert the link to a trunk link.  
• E、 None of the other alternatives apply