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
Agglutination test is - 
Select and explain. 
A. ABO incompatibility, B. VDRL, C. Weil-felix test, D. FTA-ABS
C: Weil-felix test
Answer: C: Weil-felix test 
Explanation: Weil- Felix reaction for the diagnosis of typhus fever. - The Agglutination reaction is when a paiculate antigen is mixed with its antibody in the presence of electrolytes at a suitable temperature and pH, the paicles are clumped or agglutinated. Reference : Anathanarayan & paniker's 9th edition, pg no: 108,109 <\p>