Karl Landsteiner, along with Alexander Wiener, discovered the Rh factor in 1940. This antigen, present on the surface of red blood cells, determines the Rh-positive or Rh-negative status of blood groups, which is critical for blood transfusions and pregnancy.
| LIST I | LIST II | ||
|---|---|---|---|
| A | Chop wound | I | Axe |
| B | Punctured wound | II | Needle |
| C | Bruises | III | Whip |
| D | Incised wound | IV | Knife |
| LIST I (Phenotype) | LIST II (Antibodies) | ||
|---|---|---|---|
| A | O | I | Anti-A |
| B | A | II | None |
| C | B | III | Anti-B |
| D | AB | IV | Anti-A and Anti-B |
Match List-I with List-II 
