单项选择题
A．advantages B．blossom C．brains D．brilliant E．deserve F．gravely G．head H．influence I．intelligent J．nearly K．parental L．problems M．produce N．shaped O．survives
A．Because they are painful after transplants. B．Because drugs can ease the burden of organs. C．Because the body still reacts enough to cause transplants to fail. D．Because the donor organs will fail in a very short time.