Control traffic like CDP, DTP, PAgP, and VTP uses VLAN 1 to operate, even if you change the native VLAN.
Although some books and websites said DTP is disabled if the switch port is configured as trunk or access mode (via the command “switchport mode trunk” or “switchport mode access”) but in fact DTP is still running in these modes. Please read at http://packetlife.net/blog/2008/sep/30/disabling-dynamic-trunking-protocol-dtp/. The only way to disable DTP on a switch port is to use the “switchport nonegotiate” command. But notice this command can only be used after configuring that switch port in “trunk” or “access” mode.
Therefore this is a question with no correct answer but if we have to choose an answer, we will choose answer A. At least it is correct in theory.
The Dynamic Trunking Protocol (DTP) is used to negotiate forming a trunk between two Cisco devices. The default DTP configuration for Cisco Catalyst 2960 and 3560 switches is dynamic auto.