Which provided the first source of power for factory machines during the industrial revolution?
a. nuclear energy, b. steam, c. water, d. electricity

The best answer is  B.
 Steam power technology developed slowly over a period of a few centuries. It reached practical application at the begining of the industrial revolution. The steam engine, a simple device that used boiling water to create mechanical motion that could be utilized in various kinds of useful work,    was one of the most important  technologies of the industrial revolution

Before that, water power in rivers or streams  was used to operate mills. But  this was prone to many setbacks because  mills had to be located next to running water and also in winter the water would freeze and operations would stop. But a factory using a steam engine could be located anywhere and could run the whole year round.