The transformation of wood into lithified material is known as:

• A. Metamorphism
• B. Diagenesis
• C. Lithification
• D. Fossilization

Answer: (B)

The idea being tested is how organic matter becomes a rock through burial and chemical/physical alteration. Wood turning into lithified material happens during diagenesis, the process that alters sediments and organic-rich material at low temperatures and pressures after burial. In this stage, plant material can be transformed and compacted, with chemical changes like carbonization and cementation helping it become a coal-like, lithified rock. This is distinct from metamorphism, which involves greater heat and pressure that drive new minerals and textures, and from lithification in a general sense (which is about turning sediments into rock, not specifically about organic matter like wood). Fossilization refers to preservation of the original organism more than its transformation into rock. So the appropriate term is diagenesis.