Which of the following methods can be used to break concrete into smaller pieces?

Breaking concrete into smaller pieces can effectively be accomplished through the method of dropping. This technique usually involves using the weight of a heavy object or equipment to impact the concrete surface, causing it to fracture and break apart. When a heavy load is dropped onto concrete, the sudden force exceeds the concrete's compressive strength, leading to the formation of cracks and ultimately breaking it into manageable sections.

While the other methods presented—pulling with a loader, using only tools, and a combination of droppings and tools—may have some effectiveness, they are not as direct or efficient for breaking concrete. Pulling tends to be more useful for moving or dislodging materials rather than causing them to break apart effectively. Using only tools, such as chisels or sledgehammers, can require significant manual effort and time. A combination of dropping and tools might increase efficiency, but the simplicity and effectiveness of just using dropping as a method stand out for quickly fragmenting concrete into smaller pieces.