Under what circumstances does agglutination occur during blood tranfusion even if the donor and recipient both have the same blood group ?
A. Donor is `Rh^+ "and recipient is" Rh^-`
B. Donor is `Rh^- "and recipient is" Rh^+`
C. Donor and recipient both are `Rh^+`
D. Donor and recipient have different kinds of haemoglobin
