When white phosphorus is boiled in alkaline medium, it disproportionates as:
a) P₄ + 3NaOH → PH₃ + 3NaH₂PO₂
b) P₄ + 6NaOH → 2PH₃ + 2Na₃PO₂ + 3H₂O
c) P₄ + 3NaOH → PH₃ + 3Na₃PO₄
d) P₄ + 3NaOH → PH₃ + 3NaH2PO₃