The correct option is B Ammonia
If we wanted to prepare ammonia in the laboratory, we can use cylinders of nitrogen gas and hydrogen gas and get the them to react in a vessel using suitable conditions (pressure, temperature, and catalyst).
The catch is that neither of the reactants (gases) occur as pure reagents in nature. For industrial manufacturing, procuring the reagents on a large scale at competitive prices is a tough task. Nitrogen can be obtained from air using fractional distillation/evaporation. For Hydrogen, the famous water gas shift reaction is utilized.
For the Haber-Bosch process, the following reaction is key:
Ammonia is the starting point for the manufacture of many other important nitrogen containing compounds.