In the manufacture of ${NH}_3$ in Haber's continuous flow process involving the reaction
$N_{2\left(g\right)}+3H_{2\left(g\right)}\stackrel{\left[{Fe}_2{O}_3\right]}{\rightleftharpoons }2{NH}_3\left(g\right),\Delta H=-22.08kcal$. The favourable conditions are :

The correct options are
A High pressure and low temperature due to low activation energy ($E_a$)
C High pressure and elevated optimum
The reaction is exothermic and takes place with a decrease in number of molecules of gaseous species.

Obviously high pressure and low temperature are the favourable conditions for the shift of equilibrium to products side. However, in continuous flow process, optimum elevated temperature is required to have more ${NH}_3$ due to high activation energy of the reaction.

Hence, option C is correct.