How Does the "Hole in the T Cell Repertoire" Model

Multiple Choice

How does the "hole in the T cell repertoire" model explain why some individuals may fail to respond to an antigen?

A) MHC class II molecules differ in their ability to bind and process antigen.
B) The TCR is lacking appropriate accessory molecules to fully transduce signals.
C) Some individuals lack a lymphocyte with a TCR that recognizes a specific antigen.
D) Antigen is inappropriately presented on MHC class I molecules rather than class II molecules.