Laboratory diagnosis of viral respiratory tract infections can be established by all of the following tests except:

• A. Isolation of viruses using centrifugation enchanced culture
• B. Detection of viral heamagglutination inhibiting (HAI) antibodies in a single serum specimen
• C. Detection of virud specific IgM antibodies in single serum specimen
• D. Demonstration of antigens by indirect immunofluorescence assay in nasopharyngeal washings