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
Example of heterophile antigen is ? 
Select and explain. 
A. Forssman antigen, B. Cryptococcus polysacchoride, C. Protein A of staphylococcus, D. All of the above
A: Forssman antigen
Answer: A: Forssman antigen 
Explanation: Ans. is 'a' i.e.,Forssman antigen Heterogenetic (Heterophile) specificitySame or closely related antigens occuring in different biological species, classes and kingdoms are known as heterogenetic or heterophile antigens.