For the reversible reaction : $N_2 (g) + 3H_2(g) \leftrightharpoons 2NH_3 (g) + heat$ <br> The equilibrium shifts in forward direction -

Question

( A ) by increasing the concentration of $NH_3(g)$
( B ) by increasing pressure and decreasing temperature
( C ) by decreasing the pressure
( D ) by decreasing the concentrations of $N_2 (g)$ and $H_2 (g)$