Final answer:
Karl Landsteiner is credited with identifying the ABO blood groups in 1900, which was a major advancement in transfusion medicine and saved countless lives by allowing for blood type matching.
Step-by-step explanation:
The individual associated with identifying the ABO blood groups and recognizing that human blood types are not all the same is c) Karl Landsteiner. Karl Landsteiner, an Austrian biologist and physician, made this groundbreaking discovery in 1900. His work on blood groups paved the way for safer blood transfusions by allowing for matching of patient and donor blood types.
Before Landsteiner's discovery, blood transfusions were dangerous and often fatal due to incompatibility reactions, which were not understood at the time. Blood groups are determined by the presence or absence of specific marker molecules on red blood cells. Landsteiner's identification of the four distinct blood types—A, B, AB, and O—was based on the clumping patterns he observed when serum from one person was mixed with red blood cells (RBCs) from another.
The discovery of antigens and antibodies was crucial in understanding and preventing transfusion reactions. These terms refer to the components involved in immune system responses to foreign substances in the body, which, in the case of RBCs, are the agglutinogens on the surface and their corresponding agglutinins.