To meet the requirement of summarizing the number of open and closed cases on an Account, two potential automation solutions can be used:

Option A (AppExchange): Salesforce AppExchange offers various pre-built apps and components, including those for case management, which could provide the functionality to summarize cases and categorize customer support utilization. Many apps can handle complex business requirements like case summary roll-ups and could meet the needs without custom development.

Salesforce AppExchange

Option D (Apex): Apex is Salesforce’s programming language that allows developers to implement custom logic. In this scenario, Apex could be used to create a trigger or scheduled job that calculates the number of open and closed cases and updates the Account record accordingly. Apex would allow full customization of how the open/closed case numbers are calculated and how customer support utilization (high, medium, low) is determined.