The increase in order of carbon content of the different types of coal is given by
1
Peat < Sub-bituminous coal < Bituminous coal < Anthracite
2
Peat < Bituminous coal < Sub-bituminous coal < Anthracite
3
Anthracite < Sub-bituminous coal < Bituminous coal < Peat
4
Anthracite < Bituminous coal < Sub-bituminous coal < Peat