Which sedimentary rocks are formed from mostly organic matter?

limestone commonly forms from the accumulation of calcium carbonate by various marine animals;

coal is a carbon-rich compaction of plant material which was not allowed to break down in the presence of air ...

rock salt and rock gypsum are compacted and lithified evaporites (formed by precipitating out of evaporating water);

sandstone and shale are compacted and lithified products of rock weathering, transport and deposition (don't let lithified concern you - it's just a fancy word meaning "made into rock");

conglomerate is a generic term for natural concrete - a mixture of pebbles, sands, and clays, compressed into a rock;

dolostone is a chemically altered limestone, where some of the calcium has been replaced with magnesium ...

I'd go with 2.

(2) Coal formed from the remains of dead plants, limestone is composed of millions of calcite skeletons of microscopic marine creatures.

easy 2.- coal and limestone

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IITS A....

i agree with them.