Which of the following best explains what power measures?

Power measures the rate at which work is completed or energy is transferred over time. In essence, it quantifies how quickly or efficiently work is done. When you think about power, it's useful to consider practical examples: for instance, a more powerful engine can do the same amount of work in less time compared to a less powerful engine.

In this context, other options don't accurately reflect the definition of power. The amount of energy used relates more closely to energy consumption rather than the efficiency or speed of work. The total work done over time can describe power when you take time into account, but it’s the rate aspect—how quickly that work is done—that specifically defines power. The force applied to an object is a fundamental physical quantity affecting motion, but it does not, on its own, define power without considering the distance over which that force is applied and the time taken. Power truly encapsulates the idea of completing work rapidly or transferring energy swiftly.