Final answer:
The last step in the problem-solving model is to monitor the results, which is true, as this step helps in evaluating the effectiveness of the solution over time and determining if any adjustments are required.
Step-by-step explanation:
The last step of the problem-solving model is indeed to monitor the results. Therefore, the answer to the question is A. True. In the context of problem-solving, it is crucial to not only develop a solution but also to track and assess the effectiveness of that solution over time.
By monitoring the results, one can determine whether the problem has been resolved effectively or if further adjustments are needed. This step is important to ensure that the solution has a lasting positive impact and to inform future problem-solving strategies.