$2\mathrm{B}\left(\mathrm{g}\right)\rightleftharpoons 3\mathrm{C}\left(\mathrm{l}\right)+\mathrm{D}\left(\mathrm{g}\right)+90\mathrm{kJ},$  Favourable conditions for the formation of ‘B’ according to Lechatelier's principle are

Forward reaction is exothermic, $\mathrm{\Delta H}=-90\mathrm{kJ}$

It is favoured at low temperature

Forward reaction involves decrease in the moles of gaseous species

It is favoured at high pressure

Formation of ‘B’ is backward reaction ;

$\therefore$Formation of B is favoured at high T, low P