Which one of the following lists four type of coal, arranged in the increasing order of their carbon content?
(a) Peat, Lignite, Bituminous, Anthracite
(b) Peat, Bituminous, Lignite, Anthracite
(c) Lignite, Peat, Bituminous, Anthracite
(d) Peat, Anthracite, Lignite, Bituminous
