Universal Containers (UC) has a custom Invoice object and a custom Invoice Line Item Object.

The correct answers are A. There are already two master-detail relationships on the Invoice Line Item and C. Invoice Line Item records exist without having the Invoice lookup field populated.

Salesforce allows a lookup relationship to be converted to a master-detail relationship only when the lookup field has a value on all existing records. Therefore, if any Invoice_Line_Item__c records do not have the Invoice lookup populated, Salesforce prevents the conversion.

Salesforce also limits each custom object to up to two master-detail relationships. If Invoice Line Item already has two master-detail relationships, it cannot have another master-detail relationship added or converted.

B is incorrect because custom objects can be on the detail side of master-detail relationships. D is incorrect because a roll-up summary field on Invoice is not the reason this lookup-to-master-detail conversion would be blocked.

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