Which of the following varieties of coal accounts for the maximum coal output of the world?

Answer: Option C

Bituminous varieties of coal accounts for the maximum coal output of the world. Bituminous coal or black coal is a relatively soft coal containing a tarlike substance called bitumen or asphalt. It is of higher quality than lignite coal but of poorer quality than anthracite. Formation is usually the result of high pressure being exerted on lignite.