Which of the following steps is not involved in the process of decomp…

The correct answer is Option (4) → Stratification

Decomposition is the breakdown of complex organic matter (detritus) by decomposers into simple inorganic substances such as CO₂, water and nutrients. Its important steps are fragmentation, leaching, catabolism, humification and mineralisation.

(1) Fragmentation — A step of decomposition. Detritivores such as earthworms break the detritus into smaller particles.

(2) Leaching — A step of decomposition. Water-soluble inorganic nutrients go down into the soil and get settled as unavailable salts.

(3) Catabolism — A step of decomposition. Enzymes of bacteria and fungi break the detritus down into simpler inorganic substances.

(4) Stratification — Not a step of decomposition. Stratification is the vertical layering of plants of different heights in an ecosystem.

NCERT Extract:
Decomposition – “… Similarly, decomposers break down complex organic matter into inorganic substances like carbon dioxide, water and nutrients and the process is called decomposition. Dead plant remains such as leaves, bark, flowers and dead remains of animals, including fecal matter, constitute detritus, which is the raw material for decomposition. The important steps in the process of decomposition are fragmentation, leaching, catabolism, humification and mineralisation.”
Ecosystem – Structure and Function – “… Vertical distribution of different species occupying different levels is called stratification.”