An org contains two custom objects: Building__c and Office__c. Office__c has a Lookup field to Building__c. A developer is asked to automatically populate the Number_of_Offices__c field on the…

An org contains two custom objects: Building__c and Office__c. Office__c has a Lookup field to Building__c. A developer is asked to automatically populate the Number_of_Offices__c field on the Building__c object with the count of related Office__c records anytime an Office__c record is created or deleted. The developer cannot modify the field types. Which solutionmeets the requirements?