AIIMS 2019 Botany Structure of Ovule MCQ Question

Option C is correct because it identifies the structure responsible for gas exchange in the respiratory system, specifically the alveoli, where oxygen (O₂) diffuses into the bloodstream and carbon dioxide (CO₂) is expelled. Options A, B, and D likely refer to other components of the respiratory system, such as the trachea or bronchi, which do not facilitate the primary function of gas exchange as effectively as the alveoli do. Understanding the role of alveoli is crucial for grasping how the respiratory system maintains homeostasis by regulating O₂ and CO₂ levels in the body.