Cloud Kicks wants to start tracking how many shoe subscriptions have been Sold for each...

The correct answer is A. Roll-up summary field.

Cloud Kicks wants to count how many Subscription records are related to each Shoe record. Because a master-detail relationship already exists between Subscription and Shoe__c , the app builder should create a Roll-Up Summary field on the master object.

Salesforce documentation confirms that roll-up summary fields can count the number of detail records related to a master record. Trailhead also explains that roll-up summaries display values on the master record based on directly related detail records in a master-detail relationship.

B. Lookup field and C. Master-detail field define relationships, but the relationship already exists. D. Sum field is not a Salesforce field type.

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