This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
The following diagnostic tests are useful for corresponding purposes except 
Select and explain. 
A. Ziehl-Neelsen staining - Detection of mycobacteria, B. Immunoflorescence - Detection of Influenza virus, C. Specific IgM antibodies - Immunity against Rubella, D. Specific IgM antibodies - Detection of acute infection
C: Specific IgM antibodies - Immunity against Rubella
Answer: C: Specific IgM antibodies - Immunity against Rubella 
Explanation: IgM antibody appears following an acute infection. It is not specific for a disease. Ref: Baveja textbook of microbiology; 4th edition