What is a common example of ligature that could be used for hanging?

The choice of a door knob as a common example of ligature that could be used for hanging is rooted in its physical characteristics and location within a typical environment. Door knobs are usually positioned at a height that can facilitate strangulation if a ligature is looped around them. Their sturdy construction provides a stable anchor point, making it plausible for an individual to use a ligature, such as a length of rope or fabric, to secure oneself effectively.

In contrast, the other options do not provide the same functionality or physical characteristics conducive to hanging. A couch pillow lacks the structural support needed for such an action, and while a bedside table can be sturdy, it does not easily offer a point for hanging. A window screen is typically designed to be removed or pushed aside, making it unsuitable as a secure anchor point for a ligature. Each of these reasons underscores why the door knob is the most appropriate example of ligature used for hanging among the given options.