The correct options are
A Levelling of land
B Filling of paddy fields
∙ An ecosystem is formed by the interaction of biotic and abiotic components.
∙ Any activity that harms either of the components, harms the whole of the ecosystem.
∙ Cutting down trees and plants, levelling of lands for constructuion purposes, filling of paddy fields, destroying the quality of crops by adding excessive fertilisers, etc., harms both the components and hence harms the ecosystem.
∙ On the other hand, planting more trees, conserving forests and natural resources like water and soil can help in conserving ecosystems.