Which of the following layers of epidermis contains the rapidly dividing keratinocytes?

a. Exchanging of gas: Alveoli are the primary sites for gas exchange in the lungs, where oxygen is absorbed into the blood and carbon dioxide is expelled.

b. Removing pathogens that are breathed in: This is a function of the respiratory tract's immune components, like macrophages in the alveoli, but not the primary function.

c. Containing mucus-producing goblet cells: Goblet cells are found in the respiratory tract but not in the alveoli.

d. Secreting surfactant to reduce surface tension: Alveolar cells do secrete surfactant, which is crucial for reducing surface tension and preventing alveolar collapse, but the primary function is gas exchange.

a: Basal ganglia - The basal ganglia are involved in motor control and coordination but not in respiratory regulation.

b: Parietal lobe - The parietal lobe is involved in sensory processing and spatial awareness but not in respiratory regulation.

c. Medulla: The medulla oblongata, specifically the respiratory center within it, is responsible for the involuntary control of respiration, including setting the basic rhythm of breathing and responding to changes in blood pH and oxygen levels.

d: Hypothalamus - The hypothalamus regulates various physiological processes, including temperature regulation and hormone secretion, but not respiration.