Answer:
Notifying Serena of any material changes
Step-by-step explanation:
With Serena now serving as their (Mark and debbie Calhoun) agents, it is paramount that Serena (the agent) be notified about any material changes made by the buyers. The buying agents (in this case Serena) is an individual or organization that is responsible for purchasing goods or property on behalf of another person. They are usually license professionals who search and undergo the purchasing procedure of products that their clients is interested in owning.