What was most valuable for the powering of other machines? the steam engine abundant natural resources the system of standardized parts

I would say that the correct answer here would be: Abundant natural resources.

Explanation:

This can be explained by the fact that natural resources, especially coal, oil, gas, and others, became almost the lifelines of the Industrial Revolution and permitted the development of machinery and industries. Without these natural resources, machinery would not have been easily developed. This is particularly the case of coal, which was abundantly used after the Revolution. It was from natural resources, and their use, that other more advanced technologies, such as the steam engine, evolved. Countries with such rich resources , or who had the means to extract them from countries that were rich in them, developed their technologies faster than those who either had them but could not extract them and use them efficiently, or simply did not have them.