**Core Concept**
Impression plaster is a type of dental impression material used for creating accurate models of the oral cavity. It is a hydrocolloid material that consists of a mixture of plaster of Paris and water.

**Why the Correct Answer is Right**
Impression plaster is hydrophilic due to its water-absorbing properties. This characteristic allows it to absorb excess moisture from the oral cavity, creating a stable and accurate impression. The hydrophilic nature of impression plaster enables it to form a gel-like consistency when it comes into contact with water, which helps in capturing the intricate details of the oral cavity.

**Why Each Wrong Option is Incorrect**
**Option A:** Impression plaster is not hydrophobic; it is hydrophilic, as mentioned earlier. Hydrophobic materials repel water, which is not the case with impression plaster.

**Option C:** Impression plaster is actually compatible in wet sulcus. In fact, its hydrophilic nature allows it to absorb excess moisture, making it suitable for use in areas with high water content.

**Option D:** Impression plaster is not highly viscous. Its viscosity is relatively low, allowing it to flow easily and fill the intricate details of the oral cavity.

**Clinical Pearl / High-Yield Fact**
A common mistake in using impression plaster is not allowing it to set properly, resulting in a distorted impression. To avoid this, it's essential to ensure the material is allowed to set for the recommended time before removing it from the oral cavity.

**✓ Correct Answer: B. Hydrophilic. Impression plaster is hydrophilic due to its water-absorbing properties.**