How many statements are correct about Rh factor?

(a) Erythroblastosis fetalis disease is related to it
(b) No antibodies develop in plasma in response to transfusion of Rh antigen
(c) Rh factor was discovered in Rhesus monkey
(d) In general, $R{h}^{+}$ blood cannot be transfused in $R{h}^{-}$ recipient

The correct option is C 3
A) Statement (a): Erythroblastosis fetalis, is a type of anemia in which the red blood cells of a fetus are destroyed in a maternal immune reaction resulting from a blood group incompatibility between the fetus and its mother. This incompatibility arises when the fetus inherits the Rhesus factor from the father that is absent in the mother. In other words, the foetus is ${Rh}^{+}$ while the mother is ${Rh}^{-}$.

B) Statement (a) is correct. Antibodies are developed in the plasma in response to the Rh antigen if ${Rh}^{+}$ blood is transfused to a person having ${Rh}^{+}$ blood and will be rejected by the body of the recipient.

C) Statement (a) is correct while statement (b) is wrong. Rh factor was first discovered in Rhesus monkeys and was named after them.

D) Statement (a) and (c) are correct while statement (b) is wrong. ${Rh}^{+}$ blood cannot be transfused to ${Rh}^{+}$ blood as it will result in a mismatch and the blood will be rejected. So statements (a), (c) and (d) are correct.

So the correct answer is '3'.