For the reaction \( N_{2}(g)+3 H_{2}(g)=2 NH_{3}(g), \mathbf{K}_{\mathrm{p}} \) is \( 4.3 \times 10^{-4} \) at \( 375^{\circ} \mathrm{C} \) . Calculate \( \mathbf{K}_{c^{}} \)

A 0.023

B 0.86

C 0.013