D; Hardy- Weinberg requires a very large population size so that genetic drift can be insignificant.
As a guess because they can be a right answer and some times they are not
The pathway will be;
The body cells becomes infected with a virus= then new viral proteins appear = class I MHC molecule-antigen complex displayed on cell surface.
Cytotoxic T cell is a T lymphocyte that kills cancer cells, cells that are infected or cells that are damaged in other ways. They are activated on the surface of antigen-presenting cells, which mature during the innate immune responses triggered by an infection.
