Final answer:
The correct option is C). Dead space air is the air that does not participate in gas exchange and includes anatomical dead space and alveolar dead space.
Step-by-step explanation:
Dead space air is best described as C. Air that does not participate in gas exchange. This includes both the anatomical dead space, which is air present in the airway that never reaches the alveoli, and the alveolar dead space, which involves air in the alveoli that are unable to function properly, such as those affected by disease or abnormal blood flow. The total dead space is the combination of anatomical and alveolar dead space, representing all the air in the respiratory system that does not contribute to the gas exchange process.