Answer: C) 8 moles
Step-by-step explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

According to stoichiometry of the given balanced equation:
2 moles of
decomposes to form 2 moles of

Thus 8 moles of
decomposes to form=
of

Thus 8 moles of
are produced from 8 moles of