A 57-year-old woman presents with dyspnea on exertion. Pulmonary function studies with plethysmography demonstrate an increased resting oxygen consumption and work of breathing. Which of the following will decrease the oxygen consumption of the respiratory muscles?
a. A decrease in airway resistance
b. A decrease in diffusing capacity of the lung
c. A decrease in lung compliance
d. An increase in rate of respiration
e. An increase in tidal volume