In the natural carbon cycle, which of the following paths shows carbon moving from plants to animals and then back to the atmosphere?

Introduction / Context:
The carbon cycle describes how carbon moves continuously between the atmosphere, plants, animals, and other parts of the Earth system. In school level environmental chemistry, students are expected to know how carbon dioxide from the air is taken up by plants, transferred to animals through feeding, and then returned to the atmosphere by respiration and decay. This question focuses on recognising a realistic path that carbon can follow between plants, animals, and the atmosphere.

Given Data / Assumptions:

• Carbon in the atmosphere is mainly present as carbon dioxide gas.
• Green plants take in carbon dioxide from the atmosphere during photosynthesis.
• Animals obtain carbon by eating plants or other animals.
• Both plants and animals release carbon dioxide back to the atmosphere during respiration.
• The correct option should show a complete path from plants to animals and finally back to the atmosphere.

Concept / Approach:
In the simplest land based carbon cycle, carbon dioxide from the atmosphere is fixed by plants into sugars and other organic molecules. When animals eat these plants, the carbon becomes part of their bodies. Through respiration, both plants and animals break down food molecules and release carbon dioxide back into the air. A realistic path that begins in plants, passes through animals, and ends in the atmosphere should follow this biological logic and include the return of carbon to the atmosphere as the final step.

Step-by-Step Solution:
Step 1: Identify the plant step. Plants are the main producers that fix atmospheric carbon into biomass through photosynthesis. Step 2: Identify the animal step. Animals eat plants, so carbon moves from plant tissues into animal tissues. Step 3: Identify the atmosphere step. During respiration and decay, carbon returns to the atmosphere as carbon dioxide. Step 4: Match the sequence. The path Plant ----> Animal ----> Atmosphere fits this complete flow from plant to animal to air.

Verification / Alternative check:
If we imagine a leaf on a tree, carbon in that leaf may later be eaten by a herbivore such as a cow. Inside the cow's body, the carbon enters cells and is used for energy. When the cow respires, it releases carbon dioxide to the atmosphere. This real life story clearly follows the order plant, then animal, then atmosphere. The option Plant ----> Animal ----> Atmosphere exactly matches this realistic description, which verifies our choice as correct.

Why Other Options Are Wrong:
Option A (Animal ----> Plant ----> Atmosphere) is incorrect because plants do not normally get their carbon directly from animals; they take carbon dioxide from the air. Option C (Atmosphere ----> Plant ----> Animal) shows a real path but stops at the animal and does not include return to the atmosphere, so it is incomplete for this question. Option D (Plant ----> Atmosphere ----> Animal) is not realistic because animals do not take carbon directly from the atmosphere; they eat plants or other animals.

Common Pitfalls:
Students sometimes forget that the carbon cycle is a loop and focus only on movement into living organisms. Another common mistake is to think animals breathe in carbon for food, which is incorrect. Animals breathe in oxygen and get carbon mainly by eating. Keeping a simple story in mind, where plants make food from air, animals eat plants, and both release carbon dioxide back to air, helps to avoid these confusions.

Final Answer:
The correct carbon path from plants to animals and back to the atmosphere is Plant ----> Animal ----> Atmosphere.