A Roll-up Summary Field is a powerful feature that calculates values from related records and displays them on a master record. However, this functionality is natively available only on the "Master" side of a Master- Detail relationship. For standard objects, Salesforce provides a built-in Master-Detail-like relationship between Accounts and Opportunities. Specifically, the Account object acts as the master, and the Opportunity object acts as the detail. This relationship allows a Platform Administrator to create roll-up summary fields on the Account to calculate the sum of "Total Opportunity Amount," the "Minimum Close Date," or a "Count" of all related opportunities. Other standard objects like Contacts (Option B) and Cases (Option C) have a lookup relationship to Accounts rather than a master-detail relationship, and therefore do not support native roll-up summaries20. Campaigns (Option D) also do not share this specific relationship with Accounts21. If an administrator needs to roll up data from these other objects, they would typically need to use a custom solution like Flow Builder or a third-party app, whereas Opportunities are supported natively out of the box.