Final answer:
The nurse should review the patient's Complete Blood Count (CBC) before administering clozapine to a patient with schizophrenia, as it can cause agranulocytosis and lower white blood cell count, increasing infection risk.
Step-by-step explanation:
When a nurse is reviewing the medical record of a patient with schizophrenia who has a prescription for clozapine, the lab test that should be reviewed before administering the medication is D) Complete blood count (CBC). Clozapine can have a side effect of agranulocytosis, a potentially serious reduction in white blood cell count, which is why it's critical to monitor the patient's CBC regularly. This test ensures that the patient has not developed this condition, as it could lead to serious infection due to immunosuppression.