Northern Trail Outfitters wants to change a master-detail relationship on Account to a lookup relationship with a custom object Park. The app builder…

A master-detail relationship cannot be converted to a lookup relationship if a roll-up summary field exists on the master object (Account) that aggregates data from the detail object (Park). Roll-up summary fields are a feature exclusive to master-detail relationships. To enable the conversion, any roll-up summary fields on the Account object that reference the Park object must be deleted first. This is a hard prerequisite for changing the relationship type from master-detail to lookup.

A. The Account is included in a flow process on the Park object.

The existence of a flow referencing the relationship does not block the conversion, although the flow may need to be deactivated and updated after the change.

B. The Park object needs at least one Master-Detail field for reporting.

This is incorrect. Objects do not require a master-detail relationship for reporting. Custom report types can be created for objects linked by a lookup relationship.

D. The park records have existing formulas on the Account.

This statement is ambiguous. Formula fields on the detail object (Park) that reference the master (Account) would continue to work, and formula fields cannot be created on a master object to reference a detail object.

1. Salesforce Help, Object Relationships Overview, "Notes on Converting Relationships": "You can’t change a master-detail relationship to a lookup relationship if the master object contains a roll-up summary field that summarizes fields on the detail object." This directly confirms that roll-up summary fields are a blocker.

2. Salesforce Help, Create a Roll-Up Summary Field: "A roll-up summary field calculates values from related records, such as those in a related list. You can create a roll-up summary field to display a value in a master record based on the values of fields in a detail record. The detail record must be related to the master through a master-detail relationship." This establishes the exclusivity of roll-up summary fields to master-detail relationships.

3. Salesforce Trailhead, Data Modeling, "Create Object Relationships" Unit: This module explains the characteristics of relationship types. It details that roll-up summaries are a key feature of the master-detail relationship, which is not available for lookup relationships, implicitly supporting why their existence would prevent a conversion.