When the coal reaches its hardest and the darkest form then it is termed as anthracite.
Answer: Option D
Explanation:
The hardest among the coal is called as the anthracite. It has large amount of carbon atoms and it is also regarded as the best quality of coal that is being mined.
This is mostly prevalent in South Korea, North Korea, United states, United Nations, Canada etc. This is mainly used in the steel making process and is combined with many alloys for enhancing their property.
