**Core Concept**
Pica is a disorder characterized by a persistent craving and compulsive eating of non-food substances, which can lead to poisoning due to the ingestion of harmful materials.

**Why the Correct Answer is Right**
Pica is associated with various health conditions, including iron deficiency anemia, which can cause cravings for non-food items like dirt, clay, or chalk. The ingestion of these substances can lead to poisoning due to the presence of heavy metals or other toxic substances. In iron deficiency anemia, the body's attempt to compensate for the lack of iron can lead to increased cravings for iron-rich substances, which can be obtained through the ingestion of non-food items.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect as pica is not typically associated with poisoning due to lead exposure from paint or contaminated water.
* **Option B:** This option is incorrect as pica is not typically associated with poisoning due to mercury exposure from fish or contaminated soil.
* **Option C:** This option is incorrect as pica is not typically associated with poisoning due to arsenic exposure from contaminated well water.

**Clinical Pearl / High-Yield Fact**
Pica is often seen in pregnant women, particularly in the first trimester, and can be a sign of iron deficiency anemia. Healthcare providers should be aware of this association and screen for iron deficiency anemia in pregnant women with pica.

**Correct Answer: D.**