Question 2

To enable the HTML5 drag-and-drop API, a developer should add the draggable attribute to an HTML element.

The draggable attribute is used to specify whether an element is draggable or not, thereby enabling the use of the drag-and-drop features in HTML5.

A) ondragover

The ondragover attribute is an event handler that specifies what happens when a draggable element is being dragged over a valid drop target. While it plays a role in the drag-and-drop functionality, it does not enable an element to be draggable itself.

B) draggable

The draggable attribute is specifically designed to enable an HTML element to be dragged. By setting this attribute to true, the element becomes draggable, allowing it to be part of the drag-and-drop interface in HTML5 applications.

C) ondragstart

The ondragstart attribute is an event handler that is triggered when a drag operation starts. Similar to ondragover, it does not make an element draggable; rather, it defines behavior during the drag process.

D) dragstart

Dragstart is not an attribute; it refers to an event name used in conjunction with event handlers like ondragstart. Therefore, it does not function as a method to enable the drag-and-drop capability of an element.

Conclusion

The draggable attribute is essential for enabling the drag-and-drop API in HTML5, making Option B the only correct choice. All other options relate to event handling during the drag process but do not serve to make an element draggable itself. Thus, they fail to fulfill the requirement posed by the question.