What condition is characterized by the blocking of a pulmonary artery due to a blood clot?

The condition characterized by the blocking of a pulmonary artery due to a blood clot is pulmonary embolism (PE). This occurs when a thrombus, which is a blood clot that forms in one part of the body (often the legs) and travels through the bloodstream, reaches the lungs and obstructs a pulmonary artery. This blockage can lead to significant complications including reduced blood flow, ventilation-perfusion mismatch, and can result in severe respiratory distress or even death if not treated promptly.

In contrast, pneumonia is an infection of the lungs, often with consolidation and inflammation of lung tissue, which does not involve a blood clot. Asthma is a chronic respiratory condition characterized by airway obstruction, often due to inflammation and muscle constriction, rather than a blockage caused by a clot. Chronic bronchitis is a long-term obstruction of airflow due to inflammation of the bronchial tubes, typically linked to chronic exposure to irritants, and not specifically related to blood clots. Thus, the specific definition and consequences associated with pulmonary embolism make it the correct answer in this context.