Final answer:
Adding a gaseous reactant increases its partial pressure, leading the equilibrium to shift to the right, option d) increases, right, according to Le Chatelier's Principle.
Step-by-step explanation:
Adding a gaseous reactant increases its partial pressure, causing the equilibrium to shift to the right. The correct answer is d) increases, right. Le Chatelier's Principle explains that if you increase the concentration of a reactant, the system will respond by shifting the equilibrium to the right in order to consume the additional reactant and re-establish equilibrium. This is especially the case when the reactant and product sides of the equilibrium have a different number of moles of gases. If increasing pressure favors the side with fewer moles of gas, then adding a reactant will shift the equilibrium toward the side with more moles of gas if that side also has a greater number of moles.