For the reaction

​the thermodynamic quantity which depends upon the pressure at which equilibrium is arrived at is (superscript ‘o’ represents standard state)

Correct option is D

​Thermodynamic equilibrium is a notion of thermodynamics with axiomatic status referring to an internal state of a single thermodynamic system, or a relation between several thermodynamic systems connected by more or less permeable or impermeable walls. In thermodynamic equilibrium, there are no net macroscopic flows of mass nor of energy within a system or between systems. In a system that is in its own state of internal thermodynamic equilibrium, not only is there an absence of macroscopic change, but there is an “absence of any tendency toward change on a macroscopic scale.”

Systems in mutual thermodynamic equilibrium are simultaneously in mutual thermal, mechanical, chemical, and radiative equilibria. Systems can be in one kind of mutual equilibrium, while not in others. In thermodynamic equilibrium, all kinds of equilibrium hold at once and indefinitely, unless disturbed by a thermodynamic operation.

The equilibrium constant, K_P, describes the ratio of product and reactant concentrations at equilibrium in terms of partial pressures.

With increase in pressure P, the equilibrium will shift in the direction, where the number of moles will decrease, to keep the equilibrium constant K_P constant.