Explanation:
Leukemia is a type of blood cancer characterized by an increased number of anomalous blood cells in the body. The cause of Leukemia is still not known. However, individuals with a family history of leukemia are prone to the disease. Common methods of treatment include, chemotherapy, radiation therapy, bone marrow transplant. Leukopenia is a condition characterized by decreased number of WBC(s) in the blood.Hence, the correct option is (D).