Answer:
A.role playing, practice, and discussion
Step-by-step explanation:
Since the class that is being designed has the goal of improving group decision-making and interpersonal relations, Mary should use the method of delivery that involves role playing, practice, and discussion as this method is going to encourage team work and will allow the group to practice and work on developing their skills together. The other methods are just theory and won't allow the teams to take the concepts into practice which can help them to learn faster and be able to apply everything on their jobs.