Final answer:
The common "basic" HIV test is the ELISA, and the "confirmatory" test is usually the Western blot or PCR test. These tests are critical in providing accurate diagnosis of HIV before considering further measurements like CD4 count and viral load.
Step-by-step explanation:
The common “basic” HIV test is the enzyme-linked immunosorbent assay (ELISA), which is a screening test for HIV antibodies. If ELISA comes back positive, the results require confirmation through a “confirmatory” test. The Western blot is the traditional confirmatory test that verifies the presence of HIV antibodies with greater specificity. However, a nucleic acid test (NAT), like the polymerase chain reaction (PCR), may also be used to detect the virus's genetic material directly, confirming the diagnosis of HIV. Furthermore, fourth-generation tests can detect both HIV antibodies and HIV antigens.
The answer to the student's question is 1) ELISA and Western blot as the common "basic" and "confirmatory" HIV tests respectively. The other options listed involve different stages of diagnosis or monitoring of the disease. For example, CD4 count and viral load measurements are crucial for monitoring the progression and treatment of HIV rather than initial diagnosis.