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
The term epitope refers to 
Select and explain. 
A. Complete antigen molecule, B. Hapten, C. Immunogen, D. Smallest antigenic determinant
D: Smallest antigenic determinant
Answer: D: Smallest antigenic determinant 
Explanation: None