A 15-year-old adolescent is brought to the clinic by a parent who is concerned about recent changes in behavior. The parent reports that the teen has become withdrawn, irritable, has declining grades, and has started hanging out with a new group of friends. The nurse suspects possible substance use. What is the priority nursing intervention?

Rationale: A. Recommend immediate drug testing to confirm substance use: While drug testing may be part of the assessment process, it is not the first priority. Establishing trust and gathering history from the adolescent is essential before moving to diagnostic measures. B. Reassure the parent that behavioral changes are a normal part of adolescence: Although moodiness and peer changes can occur in adolescence, the presence of multiple risk factors, withdrawal, irritability, poor academic performance, requires further assessment rather than reassurance. C. Tell the adolescent that substance use can lead to serious consequences and should be avoided: Providing education about risks is important, but doing this before assessing the situation may shut down communication and make the teen defensive. D. Ask the adolescent directly about substance use in a private, non-judgmental manner: This allows the nurse to gather accurate information in a confidential environment, promoting trust and honest disclosure which are critical for further planning and intervention.