During Tissue Transplant, What Is the Main Reason for the Rejection

During tissue transplant, what is the main reason for the rejection of the transplanted tissue?

A) Cytotoxic T cells and antibodies in the body destroy the transplanted tissue.
B) Helper T cells and antibodies in the body destroy the transplanted tissue.
C) Cytotoxic T cells and antibodies will reroute the blood supply away from the transplanted tissue, starving it to death.
D) The host body's antigens will not allow the transplanted tissue to attach to the host.
E) The host body red blood cells will not carry oxygen to the transplanted tissue.