Answer:
Coal was the energy source that was most important during the early stages of industrialization.
Step-by-step explanation:
During the early years of industrialization, the energy that was required to run machines came from the burning of coal. The coal was mined from various places in Europe and had an abundant supply.
The abundance of coal can be regarded as one of the factors behind the industrial revolution becoming successful. Later in the time, the emergence of oil gave a great substitute to coal. This is because the running of industries and transportation of goods were mainly based on the steam engines.