This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
Antigen part that is attached to antibody - 
Select and explain. 
A. Epitope, B. Paratope, C. Idiotype, D. Allotype
A: Epitope
Answer: A: Epitope 
Explanation: Ans. is 'a' i.e., Epitope Epitopeo Also known as "antigenic determinant".o It is antibody binding site of antigen.Paratopeo The part of the antibody or T cell receptor that interact with the epitope.'The idiotype is defined as the specific region of the fab portion of the Ig molecules to which antigen binds". - Harrison