The correct option is (a).
Explanation
The ecological interdependence between flora and fauna, specifically focusing on the gaseous exchange (Oxygen and Carbon Dioxide cycles) essential for survival in an ecosystem.
Statement 1 is Correct: Animals are primarily aerobic organisms that require oxygen for cellular respiration to generate energy. Plants release oxygen into the atmosphere as a by-product of photosynthesis. Consequently, animals depend on plants to replenish the atmospheric oxygen necessary for their survival.
Statement 2 is Incorrect: The balance of oxygen in the atmosphere is maintained by the cycle of photosynthesis (production of oxygen) and respiration/combustion (consumption of oxygen). Animal respiration consumes oxygen and releases carbon dioxide; it does not produce oxygen. Therefore, animal respiration alone does not maintain the oxygen balance.
Statement 3 is Incorrect: Plants require carbon dioxide as a raw material for photosynthesis to synthesize carbohydrates. Animals release carbon dioxide as a waste product of respiration, which becomes a source of carbon for plants. Thus, plants depend on animals (along with decomposers and other sources) for this essential gaseous exchange.
Key Takeaway: Plants and animals exhibit mutual interdependence regarding gaseous exchange: plants provide the oxygen required by animals, and animals provide the carbon dioxide required by plants, thereby maintaining the atmospheric balance.