Final answer:
Increasing the concentration of ammonia (NH3) increases the rate of the reverse reaction in the formation of ammonia from hydrogen and nitrogen.A is the correct answer.
Step-by-step explanation:
Increasing the concentration of ammonia (NH3) would increase the rate of the reverse reaction for the formation of ammonia from hydrogen and nitrogen.
This is in accordance with Le Chatelier's principle, which states that if there is a change in conditions for a reaction at equilibrium, the system will adjust to counteract the change. In this case, by adding more ammonia, the system tries to reduce this surplus by favoring the reverse reaction, which consumes ammonia and produces more nitrogen (N₂) and hydrogen (H₂).
Therefore, the mentioned correct option in the final answer for a factor that would increase the rate of the reverse reaction is increasing the concentration of ammonia.