During decomposition, bacterial and fungal enzymes degrade detritus i…

The correct answer is Option (3) → Catabolism

Decomposition breaks down detritus (dead plant parts, dead animals and faecal matter) into simpler inorganic substances. Its main steps are fragmentation, leaching, catabolism, humification and mineralisation. In catabolism, the enzymes of bacteria and fungi break detritus down into simpler inorganic substances. The other steps are different. Fragmentation is the breaking of detritus into small particles by detritivores such as earthworms. Humification forms humus, a dark substance that decomposes very slowly. Mineralisation releases inorganic nutrients from humus.

NCERT Extract:
Decomposition – “… The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and mineralisation. Detritivores (e.g., earthworm) break down detritus into smaller particles. This process is called fragmentation. By the process of leaching, water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts. Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is called as catabolism.”