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
All the following are Heterophile agglutination tests except 
Select and explain. 
A. Paul Bunnell test, B. Weil felix reaction, C. Cold agglutination test, D. Widal test
D: Widal test
Answer: D: Widal test 
Explanation: Widal test is just a agglutination test.