**Core Concept**
Acrodynia, also known as pink disease, is a rare condition characterized by a range of symptoms including pink or red discoloration of the hands and feet, accompanied by peeling of the skin, and other systemic manifestations. It is primarily associated with mercury exposure, particularly in children.

**Why the Correct Answer is Right**
Acrodynia is caused by the accumulation of mercury in the body, particularly in the skin, leading to its characteristic symptoms. Mercury exposure can occur through various routes, including ingestion of contaminated food or water, inhalation of mercury vapors, or direct contact with mercury-containing substances. The condition is most commonly seen in children who have ingested mercury-containing teething powders or other products.

**Why Each Wrong Option is Incorrect**
* **Option A:** Arsenic poisoning can cause a range of symptoms, including skin discoloration and peeling, but it is not specifically associated with acrodynia.
* **Option B:** Lead poisoning can cause a range of systemic symptoms, including neurological and gastrointestinal manifestations, but it is not specifically associated with acrodynia.
* **Option C:** Mercury exposure is the primary cause of acrodynia, but other heavy metals like arsenic and lead can also cause similar symptoms.

**Clinical Pearl / High-Yield Fact**
Acrodynia is a classic example of a condition caused by mercury exposure, and its symptoms should raise suspicion of mercury toxicity in children who have ingested contaminated products.

**Correct Answer:** D. Mercury exposure.