What is considered the most definitive diagnostic test for leukemia?

A. Chest X-ray is not a definitive diagnostic test for leukemia. It is more commonly used to evaluate for signs of infection, lung abnormalities, or metastasis in cancer patients, but it does not confirm leukemia. B. Urinalysis is not the definitive test for leukemia. While it may help assess kidney function or rule out other conditions, it is not used to diagnose leukemia. C. Complete blood count (CBC) is useful for detecting abnormalities that may suggest leukemia, such as abnormal white blood cell counts, but it alone cannot definitively diagnose leukemia. It is typically part of the initial evaluation. D. Bone marrow biopsy and aspiration is the definitive diagnostic test for leukemia. This test allows for direct examination of the bone marrow to confirm the presence of leukemia cells, making it the gold standard for diagnosis.