**Core Concept**
Xylitol is a sugar substitute that has been shown to have antibacterial properties, particularly against Streptococcus mutans, a primary contributor to dental caries. The mechanism of action involves interference with the bacterial cell membrane, ultimately affecting various aspects of bacterial physiology.

**Why the Correct Answer is Right**
Xylitol affects Streptococcus mutans by reducing its ability to adhere to tooth surfaces, thereby decreasing the formation of dental plaque. This is achieved through the inhibition of glucosyltransferase enzymes, which are essential for the synthesis of extracellular polysaccharides that facilitate bacterial adhesion. Additionally, xylitol reduces the virulence properties of S. mutans by decreasing the production of acid, which is a key factor in tooth demineralization and the development of dental caries.

**Why Each Wrong Option is Incorrect**
**Option A:** Reduced adhesion is indeed one of the effects of xylitol on S. mutans, but it is not the only effect. Therefore, this option is incomplete and incorrect in the context of the question.
**Option B:** While xylitol does reduce the virulence properties of S. mutans, this statement is too narrow and does not encompass the full range of effects.
**Option C:** Decreased acid production is another consequence of xylitol's action on S. mutans, but like the other options, it is not the only effect.

**Clinical Pearl / High-Yield Fact**
Xylitol's mechanism of action highlights the importance of sugar substitutes in preventing dental caries. It serves as a reminder that simple changes in dietary habits can have significant impacts on oral health.

**✓ Correct Answer: D. Anyone of the above.**