Which of the following are functions related to the expression of MHC molecules? a. To display self-peptides to test developing T cells for autoreactivity
b. To display self-peptides to demonstrate cell health
c. To display self-peptides to maintain self-tolerances
d. To display foreign peptides
e. All of the answers are correct.

e. All of the answers are correct.

Explanation:

The major histocompatibility complex (MHC) is a locus that contains several polymorphic genes. These genes are known to encode different components of the immune system, especially cell-surface proteins which present antigens to the T cell receptors during adaptive immune responses. The MHC genes are classified into Class I, Class II and Class III:

1- MHC class I genes encode cell surface molecules that present peptides (antigens) to cytotoxic T lymphocytes (i.e., killer T cells)

2- MHC class II genes encode cell surface molecules that present antigens to CD4+ T cells

3- MHC class III genes encode proteins that are not involved in antigen presentation (i.e., components of the complement cascade, cytokines, etc)

it would be c. xylem.