Final answer:
The nursing intervention that is considered as physician- or prescriber-initiated is administering a cleansing enema in preparation for radiological testing.
Step-by-step explanation:
Nursing interventions can be categorized based on the degree of nursing autonomy. In this case, the nursing intervention that is considered as physician- or prescriber-initiated is administering a cleansing enema in preparation for radiological testing. This intervention requires a physician or prescriber to order the enema, and the nurse carries out the administration.