This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': 'Antigen absent in Bombay blood group-a)  Hb)  Ac)  Bd)  D \nSelect and explain. \nA. abc, B. bc, C. acd, D. bcd', 'role': 'user'}, {'content': 'Answer: A \nExplanation: " Bhende et al (1952) from Bombay reported the very rare instatnce in which A and B antigens as well as the H\xa0antigens are absent from red cells. This is known as Bombay or OH blood"', 'role': 'assistant'}]