Each Year There Are an Estimated 250,000 People Who Could

Each year there are an estimated 250,000 people who could benefit from a bone marrow transplant.A major challenge is finding a donor with the matching complex of Major Histocompatibility (MHC) proteins a person needs.Why is it important that the MHC proteins match between the donor and recipient?

A) If they don't match,the donor's immune system will see the recipient's bone marrow as foreign.
B) MHC proteins make antibodies which could attack the recipient's immune system.
C) MHC proteins serve as inhibitors of the immune system.
D) If they don't match,the recipient's immune system will see the donor's bone marrow as foreign.
E) MHC proteins are used by cytotoxic T cells to kill bacteria,and if they don't match they won't work properly.