Which tool is used primarily to adjust transitions between clips?

The Rolling Edit Tool is specifically designed to adjust transitions between clips in a timeline. This tool allows users to change the in and out points of two adjacent clips simultaneously without affecting the overall length of the sequence. When a rolling edit is performed, one clip's duration is decreased while the adjacent clip's duration is increased, ensuring that the total runtime remains constant. This is particularly useful in video editing, as it allows for fine-tuning of transitions and ensures that the pacing of the clips is maintained, enhancing the smoothness and flow of the final edit.

The other tools listed serve different purposes: the Slip Tool adjusts the in and out points of a single clip while maintaining its position on the timeline, the Selection Tool is used for selecting clips or segments for various modifications, and the Zoom Tool is utilized for zooming in or out on the timeline or clip details, none of which are specifically focused on adjusting transitions between clips.