The correct BPMN element is Activity . In BPMN, an activity represents work performed within a process. A User Input Task is a specific type of task because it assigns work to a human participant, usually through an Appian interface or form. Appian's documentation explicitly describes the User Input Task as "an activity that assigns a task to be completed" by a user or group, and Appian's process node documentation lists User Input Task under Human Tasks while describing it as used to assign a task and associate interfaces to capture form data into a process.
The other options do not match the symbol or purpose. A Gateway controls branching or merging logic, such as XOR, OR, or AND decisions. A Flow is the connector path between nodes, typically represented by an arrow. An Event represents something that starts, interrupts, waits, or ends process execution. The displayed User Input Task performs work and pauses the process until the assigned user completes the form, so it corresponds to a BPMN task/activity. Relevant topics: Process Modeling, BPMN Elements, Workflow Nodes, Human Tasks, User Input Task, and Appian Process Modeler .