Alveolar ventilation remains constant when
the respiratory rate is increased while the volume of air per breath is decreased
the respiratory rate and the volume of air per breath are increased
the respiratory rate is decreased while increasing the volume per breath
both a and c

Both a and c (Ans. D)

Explanation:

Alveolar ventilation: It is the rate of airflow that the gas exchange between the alveoli and the external environment. It is the process where oxygen is brought into the areas of the lungs from the atmosphere and the carbon dioxide carried into the lungs in the blood (mixed venous) is removing from the body.

Alveolar ventilation is also defined as the volume of fresh air is entering the alveoli per minute, the same volume of alveolar air leaving the body per minute.  

So, Alveolar ventilation remains constant when:

1) the respiratory rate is increased while the volume of air per breath is decreased.

2) the respiratory rate is decreased while increasing the volume per breath.

substitution is the answer in this case

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