**Core Concept**
Phossy jaw, also known as phosphorus necrosis of the jaw, is a historical occupational disease that affects the jawbone. It is caused by exposure to a specific chemical element. The condition leads to necrosis of the jawbone, resulting in severe pain, swelling, and eventually, disfigurement.

**Why the Correct Answer is Right**
White phosphorus is a highly reactive and toxic form of phosphorus. When inhaled or ingested, it can cause severe damage to the jawbone, leading to the characteristic symptoms of phossy jaw. The pathophysiology involves the deposition of white phosphorus in the jawbone, causing necrosis and inflammation. The enzyme phosphorus degrader is unable to break down white phosphorus, leading to its accumulation in the body and subsequent damage.

**Why Each Wrong Option is Incorrect**
**Option B:** Red phosphorus, on the other hand, is relatively less reactive and non-toxic compared to white phosphorus. It is not associated with the development of phossy jaw.
**Option C:** Arsenic is a different heavy metal that can cause various health problems, including skin lesions and cardiovascular disease, but it is not responsible for phossy jaw.
**Option D:** Antimony is another heavy metal that can cause health problems, including gastrointestinal symptoms and cardiovascular disease, but it is not associated with phossy jaw.

**Clinical Pearl / High-Yield Fact**
Phossy jaw is a classic example of an occupational disease that highlights the importance of proper safety measures and regulations in the workplace. The condition led to significant reforms in the 19th and 20th centuries, including the establishment of stricter regulations and safety standards for workers handling hazardous chemicals.

**Correct Answer Line**
✓ Correct Answer: A. White phosphorus