Carbonaceous type of sedimentary rocks are made from

Step 1: Analyze the question The question asks what material carbonaceous sedimentary rocks are formed from. "Carbonaceous" means rich in carbon, which is the clue.

Step 2: Explain the concept Sedimentary rocks are classified by how they form:

• Mechanically formed (clastic): sandstone, conglomerate, shale. These come from broken rock particles.
• Chemically formed: rock salt, gypsum, some limestone.
• Organically formed: rocks built from the remains of living things. These are of two kinds: • Calcareous: rich in calcium carbonate, from shells and skeletons of animals (e.g. limestone, chalk). • Carbonaceous: rich in carbon, from plant material (e.g. peat, lignite, coal).

Step 3: Work through the solution Coal forms when plants such as swamp forests die and are buried under layers of sediment. Over millions of years, heat and pressure drive off water and gases. The carbon concentrates, and the vegetation changes through these stages:

Peat → Lignite → Bituminous coal → Anthracite

Now check the options:

• A. Remains of dead animals: This describes calcareous rocks such as limestone, not carbonaceous ones.
• B. Vegetative matter: This is correct. Carbonaceous rocks such as coal come from buried plant material.
• C. Molten magma: This forms igneous rocks, not sedimentary ones.
• D. Living plants and animals: Rocks form from dead, buried remains, not from living organisms.

Answer: B. Vegetative matter

Exam tip: Remember it this way: Carbonaceous = Carbon = Coal = Cut-down plants (vegetation), while Calcareous = Calcium = Creatures (animal shells).