**Core Concept**
Frostbite is a cold injury that causes tissue damage due to prolonged exposure to freezing temperatures. Rapid rewarming is a crucial step in the treatment of frostbite, and the temperature used is critical to avoid further damage.

**Why the Correct Answer is Right**
The American Heart Association and other guidelines recommend rewarming frostbite-affected areas with warm water at a temperature of 104°F (40°C) to 107°F (42°C). This temperature range is warm enough to promote blood flow and prevent further damage but not so hot that it causes burns. The rewarming process should be gradual and take at least 20-30 minutes. **Option B** is the correct answer.

**Why Each Wrong Option is Incorrect**
* **Option A:** Water temperatures below 104°F (40°C) may not be warm enough to effectively rewarm the affected tissues and may lead to further tissue damage.
* **Option C:** Water temperatures above 107°F (42°C) can cause burns and further damage to the affected tissues.
* **Option D:** Air rewarming is not recommended as it may cause further cooling of the affected tissues.

**Clinical Pearl / High-Yield Fact**
Remember the "rule of 20s" for rewarming frostbite: rewarming should take at least 20-30 minutes, and the water temperature should be between 104°F (40°C) and 107°F (42°C).

**Correct Answer:** B. 104°F to 107°F (40°C to 42°C)