Final answer:
The nurse should first call for assistance from security or colleagues. They should document the incident in the client's medical record. Administering a sedative to the aggressive client or confronting the client about the aggressive behavior are not the initial actions to take.
Step-by-step explanation:
The nurse in this situation should first call for assistance from security or colleagues. This is important to ensure the safety of both the nurse and other patients in the psychiatric unit. The nurse needs help to safely manage the aggressive client and prevent any further harm.
After calling for assistance, the nurse should document the incident in the client's medical record. This is important for accurate and complete documentation of the client's behavior, which can help inform future care plans and interventions.
Administering a sedative without proper assessment and medical orders (option c) is not appropriate, as it could have potential risks and adverse effects. Confronting the client about the aggressive behavior (option d) can also escalate the situation and is not the immediate priority.