Answer: The correct answer is "the rate of doing work".
Step-by-step explanation:
The expression for the power is as follows;
Here, P is the power, W is the work done and t is the time taken.
The unit of power is joule per second. The SI unit of power is watt. One watt is defined as one joule of amount of work is done in one second.
The power is defined as the rate of doing work. The power is directly proportional to the work done.
To increase power, increase the amount of work done in a given time or to increase power, do work in less time.
Therefore, the rate of doing work is measured by the power of a machine.