The requirement is to model a many-to-many relationship between Account and Bug__c:
Each Account (company) can report multiple bugs.
Each Bug__c can be reported by multiple accounts.
To represent a many-to-many relationship in Salesforce, we use a junction object.
Option A: Junction object between Bug__c and Account
Correct Answer.
Create a custom junction object, e.g., AccountBug__c, with two master-detail relationships:
One to Account.
One to Bug__c.
This allows linking accounts and bugs in a many-to-many fashion.
Enables reporting on which companies have reported which bugs.
This would create a one-to-many relationship (one account to many bugs), but a bug cannot be associated with multiple accounts.
Option C: Lookup field on Bug__c to Account
Incorrect.
Similar to Option B, it creates a one-to-many relationship.
Option D: Roll-up summary field of Bug__c on Account
Incorrect.
Roll-up summary fields require a master-detail relationship.
Does not address the many-to-many requirement.
Conclusion:
To allow reporting on the many-to-many relationship, a junction object between Bug__c and Account is needed, which is Option A.
Reference:
Creating Many-to-Many Relationships
Incorrect Options:
Option B: Master-detail field on Bug__c to Account
Incorrect.