Final answer:
The more severe the airway obstruction, the more decreased the peak expiratory flow rate and the more likely the FEV1 will be reduced, which is noticeable in the lower FEV1/FVC ratio seen in obstructive lung disease compared to restrictive lung disease.
Step-by-step explanation:
The question asks about the relationship between the severity of an obstruction in the airways and its effects on peak expiratory flow rate (PEFR) and the likelihood of reduced forced expiratory volume in one second (FEV1). The correct statement would be: The more severe the obstruction, the more decreased the peak expiratory flow rate and the more likely the FEV1 will be reduced. In the context of lung diseases, such as obstructive or restrictive lung disease, we look at the FEV1/FVC ratio to diagnose the type and severity of the disease. Obstructive lung disease, such as in cases of asthma or chronic obstructive pulmonary disease (COPD), is characterized by an obstruction that results in slower exhalation and reduced FEV1, causing a decreased FEV1/FVC ratio. On the other hand, restrictive lung disease, such as that caused by lung fibrosis, leads to a reduction in FVC but not necessarily a slower exhalation rate, resulting in a comparatively higher FEV1/FVC ratio.