Final answer:
When billing for an E/M service and an injection, modifier 4. 25 should be attached to the E/M service code to indicate a separate, significant service was provided.
Step-by-step explanation:
When billing for a distinct evaluation and management (E/M) service in conjunction with an injection on the same day, it is necessary to use a modifier to indicate that the services are separate and independent from each other. The correct modifier to use in this scenario is modifier 25. Modifier 25 should be attached to the E/M service code to signify that the patient's situation called for a significant, separately identifiable E/M service beyond the usual pre- and post-operative care associated with the procedure that was performed.
In summary, the correct answer is: 4) 25 attached to the evaluation and management service.
Modifier 25 is used to indicate that a significant, separately identifiable evaluation and management service was provided by the same physician on the same day as another procedure or service.
In this case, the injection is considered a procedure or service, and the evaluation and management service is distinct from it. Therefore, the modifier 25 should be attached to the evaluation and management service to indicate that it was a separate service.