Epitopes are a small portion of antigen which is also known as antigenic determinant which is recognized by the host antibodies which helps in generating the immune response against the antigen.
Neuraminidase is the antigen on the influenza virus which has multiple antibody recognition sites called epitope on which antibodies bind through its paratope region which is the antigen-binding site is an antibody.
Then these antibody binds to some Fc receptors present on immune cells and helps in initiating an immune response against this antigen. So the right answer is epitope.
