Which of the following blood groups is characterized by the absence of both A and B antigens on the surface of red blood cells and the presence of both anti-A and anti-B antibodies in the blood plasma?

💡 Solution & Explanation

Individuals with blood group O possess red blood cells that lack surface antigens A and B, making them universal red blood cell donors because recipient antibodies cannot bind to donor cells. Their plasma contains both anti-A and anti-B circulating antibodies. In contrast, blood group AB possesses both antigens with no plasma antibodies, making them universal recipients. Landsteiner discovered the ABO blood group system.