Answer is: C. The concentration of products would decrease, and the concentration of reactants would increase.
Balanced chemical reaction: (NH₄)₂CO₃(s) ⇌ 2NH₃(g) +CO₂(g) +H₂O(g).
According to Le Chatelier's Principle the position of equilibrium moves to counteract the change.
The position of equilibrium will move so that the concentration of water decreases again by reacting it with ammonia (NH₃) and carbon(IV) oxide (CO₂) and than concentration of ammounium carbonate ((NH₄)₂CO₃) increases.