During one year, the world output of coal stood at 3.94 billion metric tonnes with an average yearly price of $252\text{ per metric tonne}$. A few years afterwards, world output had fallen to 3.66 billion metric tonnes while the average yearly price dropped to $120\text{ per metric tonne}$. What could account for this decrease in the price of coal?
- Aalmost half the world’s coal reserves were in just two countries
- Bthe exhaustion of coal seams throughout the world
- Cthe switch to renewable sources of energy
- Dthe use of coal as a raw material as well as a fuel