During The Golden Age of Oil, oil's success substituted which energy source?

• A. Water power
• B. Natural gas
• C. Nuclear energy
• D. Coal

Answer: (D)

The main idea here is energy source substitution: oil rose to prominence and largely replaced coal as the dominant fuel in industry and transportation during the Golden Age of Oil. Oil offered higher energy density and cleaner handling, plus it could be refined into fuels like gasoline and diesel that powered cars, trucks, ships, and airplanes. This made it easier to move energy around and run engines with less bulk and soot than coal, leading to a widespread shift away from coal in many sectors. Water power remained important in some areas, and nuclear energy was not yet a factor in that era, so coal is the energy source oil most widely substituted during that time.