Which of the following is an example of a simple machine used in construction?

Cranes are an example of a simple machine used in construction because they utilize the principles of levers and pulleys to lift and move heavy materials. The crane's design allows for the efficient transfer of mechanical advantage, enabling workers to raise substantial weights that would be too difficult or unsafe to lift manually. This mechanical efficiency is crucial in construction scenarios, where heavy loads must be positioned accurately and safely.

While saws are important tools in construction, they are considered more complex machines rather than simple machines. Running tracks and concrete mixers also serve specific purposes in construction but do not fit the category of simple machines, which are typically defined as devices that alter the direction or magnitude of a force. Simple machines include levers, pulleys, inclined planes, wedges, screws, and wheels and axles, with cranes effectively embodying these concepts through their operational mechanisms.