Which of the following conditions can lead to decreased oxygen saturation readings?

Pneumonia can lead to decreased oxygen saturation readings because it is an inflammatory condition affecting the lungs, which impairs gas exchange. In pneumonia, the alveoli become filled with fluid or pus, making it difficult for oxygen to enter the bloodstream. As a result, patients with pneumonia may exhibit lower oxygen saturation levels on pulse oximetry readings, indicating that their lungs are not effectively oxygenating the blood.

While hypertension, bradycardia, and heart murmurs can affect overall cardiovascular health and function, they do not as directly impact the lungs' ability to oxygenate blood as pneumonia does. Conditions like hypertension might contribute to broader cardiovascular issues but typically do not produce a direct effect on oxygen saturation levels as pneumonia does.