Sleepless dilemma over 2 options in a Chemistry Question: Kc and equilibria [Urgent ):]?

Looks like college level chemistry. It's been about 6 years since I graduated, but I believe the answer would be c. The key is to push the formula to the right, which means adding more reagents to the other side for conversion or removing some of the final product so that there are more reactants available to form more product. Adding N2 won't do anything to help because both sides of the equation already have the same amount of nitrogen, so it will just reinforce equilibrium. Hope that helps.