15. Which one of following features is the characteristic of class II MHC pathway of antigen processing and presentation? (A) B1, 32 and B5 subunits of proteasomes are responsible for protein degradation (B) CD8+ TI cells are responsive T cells (C) Endoplasmic reticulum (ER) is the site of peptide loading to MHC. (D) Late endosomes and lysosomes are the site of antigen degradation (E) TAP1/2 molecules are involved in peptide transport and loading.