A nurse is planning care for a child who has severe diarrhea. Which of the following actions is the purse's priority?

Rationale: A. Introducing a regular diet is important but not the immediate priority in severe diarrhea. B. Rehydration is the most critical initial step to prevent or treat dehydration and shock. C. Maintaining fluid therapy is important after rehydration is initiated but not the first action. D. Assessing fluid balance is necessary but secondary to initiating rehydration.