Pathology Although more than 400 blood groups have been identified,the ABO blood group system remians the mostimpoant in clinical medicne because : A It was the first blood group system to be discovered B It has four different blood groups A,B, AB, O (H). C ABO(H) antigens are present in most body tissues and fluids. D ABO(H) antibodies are invariably present in plasma when persons RBC lacks the corresponding antigen 💡 Explanation Although more than 400 blood groups have been identified,the ABO blood group system remians the mostimpoant in clinical medicne because : ✓ Correct Answer: D. ABO(H) antibodies are invariably present in plasma when persons RBC lacks the corresponding antigen