Consider the system at equilibrium:

${\mathrm{NH}}_4\mathrm{HS}\left(s\right)\rightleftharpoons {\mathrm{NH}}_3\left(g\right)+{\mathrm{H}}_2\mathrm{S}\left(g\right)\mathrm{\Delta }H>0$

Factors which favour the formation of more ${\mathrm{H}}_2\mathrm{S}\left(\mathrm{g}\right)$ include which of the following?

(P) adding a small amount of ${\mathrm{NH}}_4\mathrm{HS}\left(\mathrm{s}\right)$ at constant volume

(Q) increasing the pressure at constant temperature

(Q) increasing the pressure at constant temperature