This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
[{'content': 'Preformed antibodies cause \nSelect and explain. \nA. Hyperacute rejection, B. Acute rejection, C. Chronic rejection, D. Acute humoral rejection', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Rejection- Antibody mediated Humoral or hyperacute rejection When preformed antidonor antibodies are present in circulation of recipient Previous rejection of a transplant Multiparous women Prior blood transfusions Mechanisms of injury - complement dependent cytotoxicity, inflammation, ADCC. Target is graft vasculature - rejection vasculitis', 'role': 'assistant'}]