Which node signifies the end of alternative sequences in an activity?

The correct choice identifies the merge node, which plays a crucial role in representing the end of alternative sequences in an activity. In the context of activity diagrams and process flows, a merge node combines different incoming flows that may have resulted from various conditional paths taken during the process.

When alternative paths are employed—such as those defined by decision points in a flow—once the various branches have executed, the merge node signifies that they converge back into a single flow. This allows the process to return to a unified path, ensuring that various alternatives can be managed appropriately.

This structure is particularly important in modeling as it clearly delineates where multiple alternatives conclude and the flow of control continues in a consistent direction. The presence of a merge node streamlines the representation of scenarios and clarifies the logic in complex processes. By using this node, designers can depict a seamless transition from multiple possibilities back into a single process flow, which is essential for the clarity of the model being developed.