Aaleyah Has Previously Donated Blood to Her Cousin Mohammed for a Blood

Aaleyah has previously donated blood to her cousin Mohammed for a blood transfusion.However,a bone marrow transplant from Aaleyah to Mohammed may not be possible because

A) even though Aaleyah's blood type is a match to Mohammed's,her MHC proteins may not be a match.
B) a blood type match is less stringent than a match required for transplant because blood is more tolerant of change.
C) for each gene,there is only one blood allele but many tissue alleles.
D) Aaleyah's class II genes are not expressed in bone marrow.
E) Mohammed's immune response has been made inadequate before he receives the transplant.