Which of the following is the correct sequence of phases of Biotic succession?Select the correct answer from the code given below:

1. A

   Ecesis - Migration - Reaction – Stabilisation

   Option (a) incorrectly places ecesis before migration, violating the fundamental ecological principle that pioneers must first arrive at a barren area before they can establish themselves.

2. B

   Ecesis - Migration - Stabilisation – Reaction

   Option (b) lists stabilisation before reaction, which contradicts the well-established chronological sequence where community modification of the environment always precedes the final climax stage.

3. C

   Migration-Reaction - Stabilisation - Ecesis

   Option (c) disrupts the sequence by placing reaction immediately after migration, completely omitting the essential establishment phase known as ecesis.

4. D

   Migration-Ecesis- Reaction - Stabilisation

   Option (d) correctly outlines the standard sequential phases of biotic succession, starting with migration of propagules, followed by ecesis for establishment, reaction where the community modifies the habitat, and finally reaching stabilisation in the climax community. This option accurately represents the universally accepted ecological succession model.

Summary. Official key is (d) Migration-Ecesis-Reaction-Stabilisation. The question tests the fundamental stages of ecological succession in bare areas. Option (a) scrambles the arrival and establishment steps. Option (b) places stabilisation prematurely before community reaction. Option (c) misses ecesis entirely. Thus, only option (d) maintains the correct biological progression.