Answer:
d
Step-by-step explanation:
a) This is not an equation.
b) This is not an equation.
c) The reactant side has 1 Na and 2 O while the product side has 2 Na and 2 O, therefore it is not balanced
d) The reactant side has 4 H and 4 O and the product side has 4 H and 4 O, therefore it is balanced.