**Core Concept**
Tissue stops in an impression tray are used to prevent the impression material from flowing into the sulcus or around the gingival margin, ensuring accurate representation of the gingival contour and preventing distortion of the final impression. This is a critical aspect of dental impression making, particularly in the context of removable partial dentures.

**Why the Correct Answer is Right**
The use of tissue stops helps to maintain the natural gingival architecture by preventing the impression material from flowing into the sulcus or around the gingival margin. This is achieved by creating a physical barrier that prevents the impression material from seeping into these areas, thereby ensuring accurate representation of the gingival contour. By doing so, the final impression accurately reflects the patient's oral anatomy, which is essential for the fabrication of a well-fitting removable partial denture.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because tissue stops are not used to prevent the impression material from flowing into the oral cavity.
**Option B:** This option is incorrect because tissue stops are not used to prevent the impression material from setting too quickly.
**Option C:** This option is incorrect because tissue stops are not used to prevent the impression material from being dislodged during the impression-making process.

**Clinical Pearl / High-Yield Fact**
A common mistake in dental impression making is failing to properly use tissue stops, leading to inaccurate representation of the gingival contour and potential problems with the final prosthesis. To avoid this, it is essential to carefully place tissue stops in the impression tray before taking the impression.

**Correct Answer: D. Prevents impression material from flowing into the sulcus or around the gingival margin.**