Concept:An ecosystem is defined by the interaction between living organisms and their non-living environment.
Explanation:An ecosystem includes both biotic components (plants, animals, humans) and abiotic components (soil, water, air, sunlight).
It is not just the sum of these parts, but the dynamic interrelationship between them.
Option A lists only living beings, so it is incomplete.
Options C and D mention only Earth’s physical spheres, missing the biological interactions.
Only option B correctly highlights that the ecosystem is formed by the interrelationship between organisms and their surroundings.
This interaction drives energy flow, nutrient cycling, and ecological balance.
Answer:Option B – interrelationship between organisms and their surroundings