Final answer:
Modifier 4. 25 should be attached to the evaluation and management service when it is a distinct service provided along with an injection, not to the injection itself.
Step-by-step explanation:
When a distinct evaluation and management (E&M) service is billed in conjunction with an injection, and these are separate and significant services, the correct modifier that must be attached is modifier 25. This modifier is attached to the E&M code to indicate that on the day a procedure or service identified by a CPT code was performed, the patient's condition required a significant, separately identifiable E&M service above and beyond the other service provided or beyond the usual preoperative and postoperative care associated with the procedure that was performed. Hence, the correct answer is option 4: 25 attached to the evaluation and management service.
If a distinct evaluation and management service is billed with an injection, the modifier that must be attached is 25 attached to the evaluation and management service. The modifier 25 is used to indicate that the evaluation and management service is a separate and distinct service from the injection.