Which component is used to prevent falls during construction?

The correct choice is the component referred to as a guard. Guards are crucial in construction settings as they provide a protective barrier that helps prevent falls from elevated surfaces. They are typically installed at edges of platforms, scaffolds, and other elevated work areas to create a secure environment for workers. Their design ensures that individuals cannot accidentally walk off the edge, reducing the risk of serious injuries from falls.

While scaffolds, railings, and harnesses all play important roles in safety during construction, they serve different purposes. Scaffolds provide a temporary structure for workers to reach high places, railings are specific types of barriers usually found at the edges of stairs or decks, and harnesses are personal protective equipment that secures a worker to an anchorage point. They focus on individual fall protection rather than creating a comprehensive safety barrier as guards do. Thus, guards are specifically designed to prevent accidental falls, making them the best answer to the question.