Correct Option: B

Rh factor was discovered by Karl Landsteiner. A child of Rh⁺ man will be Rh⁺ whether the mother is Rh⁺ or Rh^-. If the mother is Rh⁺ then there will be no problem but if mother is Rh^- so when the blood of Rh⁺ child (in womb) mixes with the blood of Rh^- mother then some antibodies in mother’s blood are formed against Rh⁺ factor which coagulate the womb blood causing death. If birth takes place then there is a possibility of child death in early years. This in known as erythroblastosis foetalis. In most cases the Ist pregnancy may succeed but after that it fails.