Which of the following conditions causes erythroblastosis fetalis?

1. Mother ${\mathrm{Rh}}^{+\mathrm{ve}}$ and fetus ${\mathrm{Rh}}^{-\mathrm{ve}}$

2. Mother ${\mathrm{Rh}}^{-\mathrm{ve}}$ and fetus ${\mathrm{Rh}}^{+\mathrm{ve}}$

3. Both mother and fetus ${\mathrm{Rh}}^{-\mathrm{ve}}$

4. Both mother and fetus ${\mathrm{Rh}}^{+\mathrm{ve}}$

Erythroblastosis fetalis is caused when:

1. Rh^– female & Rh⁺ male

2. Rh⁺ female & Rh^– male

3. Rh⁺ female & Rh⁺ male

4. Rh^– female & Rh^– male