Sodium hydroxide and sodium metal react to form sodium oxide and hydrogen. Which of the following balanced equations represents this reaction?
a) 2NaOH + 2Na → Na₂O + H₂
b) 2NaOH + 2Na → 2Na₂O + H₂
c) NaOH + 2Na → Na₂O + H2
d) 2NaOH + 2Na → 2Na₂O + 2H₂