Which is the appropriate first-aid response for a person suffering from heatstroke?

The appropriate first-aid response for a person suffering from heatstroke includes moving them to a cooler environment, preferably indoors or in the shade. Remove any excess clothing and apply cool water to their skin, or use ice packs on areas like the neck, armpits, and groin to help lower their body temperature. Offer cool fluids if the person is conscious and able to drink, but avoid caffeine or alcohol. Seek emergency medical assistance immediately, as heatstroke can be life-threatening.