For the reaction `PCI_5(g) iff PCl_3(g) + Cl_2(g)` the forward reaction at constant temperature is favoured by
(1) introducing an inert gas at constant volume
(2) introducing chlorine gas at constant volume
(3) introducing an inert gas at constant pressure
(4) decreasing the volume of the container
(5) introducing PCl, at constant pressure

Explanation

(3) introducing an inert gas at constant pressure
(5) introducing PCl, at constant pressure