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
A farmer presenting with fever off-and on for the past 4 years was diagnosed to be suffering from chronic brucellosis. All of the following serological tests would be helpful in the diagnosis at this state except - 
Select and explain. 
A. Standard Agglutination test, B. 2 Mercapto-ethanol test, C. Complement fixation test, D. Coomb's test
A: Standard Agglutination test
Answer: A: Standard Agglutination test 
Explanation: None