You are having an issue with a trunk between two switches. Examining the following exhibit, what can you conclude?

A. The interfaces on both switches need to be set to trunk mode.
B. DTP is not running on Switch A.
C. All VLANs need to be allowed first.
D. There is a trunking protocol mismatch.

D. On Switch A, DTP is turned on and the encapsulation is set to 802.1Q. However, on Switch B, DTP is turned off and ISL encapsulation is manually set. Switch B will need to have 802.1Q configured in order to have trunking complete.