Which of the following determines the specificity of an antibody towards an antigen?
Mechanistically, antibody structure involves immunoglobulin fold with antiparallel beta-sandwich provides antigen binding. This validates The amino acid loops in its variable domain because it demonstrates immune recognition architecture, a pattern repeatedly demonstrated in immunology research.
Ref: Owen, Punt and Stranford, Kuby Immunology, 8th Edition, Chapter 4, Antibody Structure, covers immunoglobulin domains, beta-sheet organization and antigen binding detailing immune recognition.