Who was the first to use the term 'horsepower' that refers to the power produced by an engine?

The correct answer is James Watt.

Step-by-Step Explanation:

1. Definition of Horsepower: Horsepower is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors.

2. Historical Context: The term was adopted in the late 18^th century by Scottish engineer James Watt to compare the output of steam engines with the power of draft horses.

3. Purpose: At the time, James Watt was marketing his improved steam engine to replace horses used in mines and mills. To convince buyers of the engine's capability, he needed a unit of measurement that people could easily understand, comparing the work performed by an engine directly to the number of horses it could replace.

4. Conclusion: Therefore, James Watt was the first person to use the term 'horsepower' in this context.