Final answer:
Flow cytometry for CD5 and CD23 is used to confirm the diagnosis of CLL.
Step-by-step explanation:
The test that can be used to confirm the diagnosis of CLL (Chronic Lymphocytic Leukemia) is Flow cytometry for CD5 and CD23. Flow cytometry is an automated, cell-counting system that uses fluorescently labeled antibodies to quantify cells of a specific type in a complex mixture. In the case of CLL, flow cytometry can identify the presence of CD5 and CD23 on the surface of the lymphocytes, which is characteristic of this type of leukemia.