Answer:
A. Petroleum
Step-by-step explanation:
According to data from 2017 of the U.S. Energy Information Administration, over 80% of electricity is generated from fossil fuels. Fossil fuels are formed throughout thousands of years from organic material and are the primary energy source (worldwide). The main fossil fuels are petroleum, natural gas, and coal.
The U.S. Energy Information Administration stated that around 40% of the energy was generated by petroleum, followed by natural gas, and finally coal.