Final answer:
A pulmonary angiogram is the definitive test for diagnosing a pulmonary embolism, providing a direct visualization of blockages in the pulmonary arteries.
Step-by-step explanation:
A definitive diagnosis of pulmonary embolism (PE) can be made by a pulmonary angiogram. This imaging test provides a clear picture of the blood flow in the lungs and is the most accurate way to diagnose a PE. While other tests like arterial blood gas (ABG) analysis, chest x-rays, and ventilation-perfusion scans can suggest a PE, they are not definitive. A pulmonary angiogram directly visualizes the blockage in the pulmonary arteries.