Given below are two statements, one is labeled as Assertion (A) and other as Reason (R): Assertion (A) : Various components of an ecosystem are not interdependent. Reason (R) : Human activities have the impacts on the environment. Select the correct answer using the codes given below. Codes:

The correct answer is D. The assertion is false. Ecosystem components, whether biotic (producers, consumers, decomposers) or abiotic (soil, water, air, temperature), are tightly interdependent. Energy flows through food chains, nutrients cycle through biogeochemical cycles, and removing one component disturbs the whole system. That interdependence is the basic principle of ecology.

The reason is true. Human activities such as deforestation, industrial emissions, mining and overuse of fertilisers alter air, water, soil and biodiversity, so humans clearly affect the environment. But since the reason is about human impact and not about interdependence, it does not explain the assertion, and in any case the assertion is wrong.

• Option A fails because the assertion is false.
• Option B fails for the same reason.
• Option C is wrong because the reason is true, not false.

Core concept: ecosystem structure and function (energy flow, nutrient cycling). For Mains, this links to environmental degradation and sustainable development, as ecosystem services collapse when interlinkages are broken.

Trap: candidates see that the reason is true and pick C, or they read the assertion loosely and think a true-looking reason must explain it. Check each statement separately first.