The reaction below represents the Haber process for the industrial production of ammonia.

\[\begin{array}{*{20}{l}} {{{\text{N}}_2}{\text{(g)}} + 3{{\text{H}}_2}{\text{(g)}} \rightleftharpoons {\text{2N}}{{\text{H}}_3}({\text{g)}}}&{\Delta {H^\Theta } = - 92{\text{ kJ}}} \end{array}\]

The optimum conditions of temperature and pressure are chosen as a compromise between those that favour a high yield of ammonia and those that favour a fast rate of production. Economic considerations are also important.

Which statement is correct?

A.     A higher temperature would ensure higher yield and a faster rate.

B.     A lower pressure would ensure a higher yield at a lower cost.

C.     A lower temperature would ensure a higher yield and a faster rate.

D.     A higher pressure would ensure a higher yield at a higher cost.

D