Which attribute should a developer add to an HTML element to enable the HTML5 drag-and-drop application programming interface (API)?

The ondragover event handler specifies a script to be run when an element is being dragged over a valid drop target. While it plays a role in the drag-and-drop process by managing what happens during a drag operation, it does not itself make an element draggable. This attribute is more about the event handling rather than defining the draggable nature of an element.

The ondragstart event handler is executed when the user starts dragging an element. While it is important for initiating the drag operation, it does not define whether the element itself can be dragged. Thus, it is not the appropriate attribute to enable drag-and-drop functionality.

Dragstart is not an attribute but rather an event that is fired when a drag operation starts. Like ondragstart, it is part of the event handling mechanism in the drag-and-drop API but does not apply to making an element draggable. Therefore, it does not fulfill the requirement of enabling the drag-and-drop API.