**Core Concept**
Indirect pulp capping is a dental procedure that involves placing a medicated dressing over a tooth with a partially decayed pulp to allow the remaining healthy pulp tissue to recover. The ideal material for indirect pulp capping should have biocompatibility, promote pulp repair, and prevent bacterial contamination.

**Why the Correct Answer is Right**
Calcium hydroxide (Ca(OH)2) is the most ideal material for indirect pulp capping due to its ability to promote pulp repair and prevent bacterial contamination. It forms a hard, impermeable layer on the surface of the pulp that protects it from bacterial invasion and allows the remaining healthy pulp tissue to recover. Calcium hydroxide also has a high pH, which helps to neutralize acidic byproducts of bacterial metabolism and creates an environment conducive to pulp repair.

**Why Each Wrong Option is Incorrect**
* **Option A:** Zinc oxide-eugenol cement is a poor choice for indirect pulp capping because it can be toxic to dental pulp tissue and may cause pulp necrosis.
* **Option B:** Mineral trioxide aggregate (MTA) is not the best choice for indirect pulp capping because it is more commonly used for direct pulp capping and as a root-end filling material.
* **Option D:** Glass ionomer cement is not ideal for indirect pulp capping because it can be too acidic and may cause pulp irritation.

**Clinical Pearl / High-Yield Fact**
When selecting a material for indirect pulp capping, it's essential to consider the material's biocompatibility, ability to promote pulp repair, and resistance to bacterial contamination.

**Correct Answer: C. Calcium hydroxide (Ca(OH)2)**