Answer is A.The changes in species composition in a community over time as species colonize and area.
Plant succession is the evolution of plant communities at a barren place over time beginning from pioneer species to climax vegetation. The plant community changes the soil and micro-climate at each stage of the succession. This helps to establish another group of species. This means as the succession develops one community of plants is replaced by another and eventually a climax community is reached where the vegetation is in a state of equilibrium with the environment and there is no further addition of new species
