Step 1: Understanding the term "niche".
\nIn ecology, a niche signifies a species' role or position within its environment. This encompasses its interactions with biotic factors (living organisms, such as predators, prey, and competitors) and abiotic factors (non-living conditions, like temperature, light, rainfall, and soil nutrients). \n\n \n
Step 2: Differentiation from other ecological terms.
\n- A habitat is an organism's "address" (its location).
\n- A niche is its "profession" (its function and interactions).
\n- An ecotone is the transitional zone between two ecosystems.
\n- Niche definition includes only abiotic factors; this is incomplete. \n\n \n
Step 3: Evaluate options.
\n- (B) Incorrect → A niche involves both abiotic and biotic factors, not just abiotic.
\n- (C) Incorrect → This describes an ecotone gradient, not a niche.
\n- (D) Incorrect → A transition zone is synonymous with an ecotone, not a niche.
\n- (A) Correct → Aligns with the complete ecological definition of a niche. \n\n \n\[\n\boxed{\text{Interaction with biotic and abiotic factors of the environment}}\n\] \n\n\n% Quicktip