A chemical equilibrium between gaseous reactants and products is shown.

N2(g) + 3H2(g) ⇌ 2NH3(g)

How will the reaction be affected if the pressure on the system is decreased?

It will shift toward the reactant side because the reactant side has more moles of gas than the product side.
It will shift toward the product side as there are more oxygen atoms in the gas on the product side.
It will shift toward the reactant side as there is lower pressure on the reactant side.
It will shift toward the product side as there is higher pressure on the product side.