Final answer:
A nurse would most likely suspect postpartum psychosis when a woman presents with delirium, which is characterized by a break in reality and could include delusions, hallucinations, and disorganized behavior.
Step-by-step explanation:
The symptom that would most likely lead a nurse to suspect that a woman is experiencing postpartum psychosis is A) Delirium. Postpartum psychosis is a rare but serious mental health condition that can occur after childbirth, characterized by a break in reality. Symptoms can include delusions or hallucinations, disorganized speech or behavior, delirium, and extreme changes in mood or behavior. While feelings of guilt, sadness, and insomnia are also concerning and can be associated with postpartum depression, delirium is more indicative of the more severe condition of postpartum psychosis.