This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
True about widal test: 
Select and explain. 
A. Anti-0 antibody persists longer, B. 0 antigen of S. paratyphi is used, C. H-antigen is most immunogenic, D. Felix tube is used for 'H' agglutination lnar
C: H-antigen is most immunogenic
Answer: C: H-antigen is most immunogenic 
Explanation: Ans. is. 'c' i. e., H-antigen is most immunogenic