Final answer:
The Haber-Bosch process produces ammonia (NH3), making option C: NH3 the correct answer.
Step-by-step explanation:
The reactive nitrogen compound produced using the Haber-Bosch process is ammonia (NH3). This process involves a chemical reaction where nitrogen (N2) gas reacts with hydrogen (H2) gas under high pressure and temperature in the presence of a catalyst to form ammonia. As per the options provided, the correct answer is C: NH3.