A turbocharger is powered by __________, while a supercharger is powered by __________.

The correct answer accurately describes the operational principles of both a turbocharger and a supercharger. A turbocharger is powered by exhaust gases, which are expelled from the engine. These gases drive a turbine connected to a compressor, allowing the turbocharger to increase the amount of air entering the engine, which in turn improves power output and fuel efficiency.

On the other hand, a supercharger is powered by the engine itself. It is an internally driven compressor that operates directly off the engine's crankshaft. This means it uses its own power source to compress the intake air, increasing the engine’s air intake for better performance, but it does so at the cost of some of the engine's overall power output.

Other options do not accurately capture this relationship. For instance, stating that a turbocharger is powered by "fuel" or that a supercharger is powered by "externally driven compressor" misrepresents the core functionality and the source of power for each component. Understanding the distinctions between these devices is essential for grasping their application in enhancing engine performance.