Which one of the following statements is true with regard to processing and presentation of protein antigens?

Q. Which one of the following statements is true with regard to processing and presentation of protein antigens?

(A) In the class II MHC pathway, protein antigens in the cytosol are processed by proteasomes

(B) In the class I MHC pathway, extracellular protein antigens are endocytosed into vesicles and processed

(C) In the class I MHC pathway, transporter associated antigen processing (TAP) protein is required for translocating processed peptides generated in the cytosol

(D) Invariant chain in endoplasmic reticulum is involved in transport of peptides and loading of class I MHC

Ans: Option C