he network administrator is trying to add Switch1 to the network， but the 802.1Q trunk is not  coming up. Switch1 was previously tested in the laboratory and its trunk configuration worked fine.  What are three possible causes of this problem？（）

• A、The trunking configuration mode on Switch1 is set to Off.
• B、The trunking configuration mode on the other end is set to On.
• C、The trunking configuration mode on the other end is set to Desirable.
• D、Cisco Discovery Protocol is not running on the other end.
• E、There is a VTP domain name mismatch.
• F、Switch1 does not support 802.1Q