Final answer:
The treatment for severe hypothermia is to gradually rewarm the patient using warm blankets and heat packs. Therefore, the correct option is B.
Step-by-step explanation:
When a patient is experiencing severe hypothermia, the most appropriate treatment is to gradually rewarm the body using warm blankets and heat packs (Option B). Rapidly rewarming with hot water immersion (Option A) can actually lead to complications such as rewarming shock, where blood rushes back to the surface of the body too quickly. Administering cold fluids (Option C) would further lower the core temperature and worsen the hypothermia. Placing the patient in a cold environment (Option D) would only increase the risk of further heat loss. Therefore, the best option is to gradually rewarm the patient using warm blankets and heat packs.