**Core Concept**
Gas gangrene is a life-threatening condition caused by Clostridium perfringens (formerly known as Clostridium welchii) infection, resulting in tissue death and gas production due to the bacterial toxin alpha-toxin. The primary treatment involves removing the infected tissue and administering antibiotics.

**Why the Correct Answer is Right**
The best treatment to prevent gas gangrene involves prompt surgical debridement of the affected area to remove the source of bacterial infection. This is followed by administering antibiotics such as penicillin, which effectively inhibits the growth of Clostridium perfringens by interfering with cell wall synthesis. The antibiotic also helps in reducing the severity of the infection by preventing further toxin production.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect because antitoxin therapy is not the primary treatment for gas gangrene, although it may be used as an adjunct to antibiotics.

**Option B:**
This option is incorrect because hyperbaric oxygen therapy has some benefits in reducing the severity of gas gangrene by inhibiting bacterial growth, but it is not the best treatment for preventing the condition.

**Option C:**
This option is incorrect because amputation may be required in severe cases of gas gangrene, but it is not a preventive measure.

**Clinical Pearl / High-Yield Fact**
The key to managing gas gangrene lies in early recognition and prompt surgical intervention, which can significantly improve patient outcomes.

**Correct Answer:** D. Penicillin