Answer
When a Rh$^{-}$ person first receives Rh$^{+}$ blood transfusion reaction does not occur because there are no anti-Rh$^{+}$ antibodies and they are created after the person receives Rh$^{+}$ blood for the first time, so when the same person gets another transfusion containing Rh$^{+}$ there are already Rh$^{+}$ antibodies in his body, causes transfusion reaction.
Work Step by Step
Same as above.
