The potential for hemolytic disease of the newborn occurs when

A)maternal Rh⁺ cells enter an Rh⁻ fetus.
B)fetal Rh⁺ cells enter an Rh⁻ mother.
C)maternal Rh⁻ cells enter an Rh⁺ fetus.
D)fetal Rh⁻ cells enter an Rh⁺ mother.
E)fetal Rh⁺ cells enter an Rh⁺ mother.