## **Core Concept**
The question tests knowledge of the composition of dental plaque, specifically the sticky polysaccharide involved. Dental plaque is a biofilm or mass of bacteria that grows on surfaces within the mouth. It is a complex structure composed of bacteria, saliva, and various polysaccharides.

## **Why the Correct Answer is Right**
The correct answer, **Dextrans**, are a type of sticky polysaccharide produced by certain oral bacteria, such as *Streptococcus mutans*. These bacteria convert sucrose into dextrans, which are glucans with alpha-glycosidic linkages. Dextrans play a critical role in the formation and adherence of dental plaque to tooth surfaces, contributing to tooth decay and other oral health issues.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While glycans are a broad category of polysaccharides that can be involved in various biological processes, they are not specifically identified as the sticky polysaccharides in dental plaque.
- **Option B:** Levans are another type of polysaccharide produced by oral bacteria, but they are not as prominently associated with the sticky properties of dental plaque as dextrans.
- **Option C:** This option seems to be a placeholder and does not provide a recognizable polysaccharide related to dental plaque.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that *Streptococcus mutans* is a primary bacterium associated with dental caries due to its ability to produce acid from fermentable carbohydrates and its role in forming sticky dextrans that adhere to tooth surfaces.

## **Correct Answer:** D. Dextrans