Final answer:
B. Vomiting. The nurse should identify vomiting as an indication that the client has heat exhaustion.
Step-by-step explanation:
The nurse should identify vomiting as an indication that the client has heat exhaustion. Heat exhaustion is a condition caused by prolonged exposure to high temperatures and excessive sweating, leading to dehydration and electrolyte imbalances. Vomiting can occur as a result of these imbalances and is a common symptom of heat exhaustion.