What is the action of a switchport set to mode dynamic desirable?

A switchport configured to mode dynamic desirable actively participates in Dynamic Trunking Protocol (DTP) negotiations. Specifically, this mode not only listens for DTP frames but also sends out DTP requests to negotiate trunking with the other end of the link. When both connected switches are set to dynamic desirable, they work together to establish a trunk link as per the DTP protocol, determining whether to initiate a trunk or remain in access mode based on the capabilities of both ends.

In contrast, options that imply a lack of engagement in DTP, such as merely listening for requests, refusing negotiations, or setting the port to solely function as an access port, do not accurately reflect the active nature of dynamic desirable mode. Thus, the correct choice identifies the proactive behavior of the switchport in fostering trunk negotiations through DTP.