[Reference:Roll-Up Summary Field Considerations, C. The trigger may fire multiple times during a transaction:, Triggers can execute multiple times within a single transaction, especially when there are operations such as updates to the parent record caused by roll-up summary fields or workflows., Developers should implement logic to ensure that the trigger handles multiple executions correctly (e.g., using a static variable to prevent recursion)., Reference:Apex Trigger Best Practices, Why not the other options?, B. Duplicate rules are executed once all DML operations commit to the database:, This is incorrect because duplicate rules executebeforethe DML operation is committed. Duplicate rules prevent duplicate records from being created or updated before the database operation occurs., Reference:Duplicate Rules Execution, D. The validation rules will cause the trigger to fire again:, This is incorrect because validation rules do not cause triggers to fire again. Validation rules validate the record and may prevent DML operations, but they do not independently re-trigger the Apex trigger., References:, Trigger Context and Recursion, Roll-Up Summary Field Documentation, , ]