**Core Concept**
Brudevold's solution is a type of fluoride varnish used in dentistry for caries prevention. It contains a specific compound that helps in the remineralization of tooth enamel and inhibition of acid production by bacteria.

**Why the Correct Answer is Right**
Brudevold's solution contains sodium fluoride as its active ingredient. Sodium fluoride works by releasing fluoride ions that help in the formation of fluorapatite, a more resistant form of tooth enamel. This process of fluorapatite formation helps in the remineralization of tooth enamel and makes it more resistant to acid attacks by bacteria, thereby preventing tooth decay.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not the correct active ingredient in Brudevold's solution. While fluoride is indeed the key component, the specific compound used in Brudevold's solution is sodium fluoride, not calcium fluoride.
**Option B:** This option is incorrect because it is a different type of fluoride varnish altogether. Other types of fluoride varnishes may contain different compounds, but sodium fluoride is the specific compound found in Brudevold's solution.
**Option C:** This option is incorrect because it is not related to the composition of Brudevold's solution. Sodium fluoride is the active ingredient, and other compounds may be added as excipients or stabilizers, but they are not the primary active ingredient.

**Clinical Pearl / High-Yield Fact**
It is essential to note that Brudevold's solution is a type of fluoride varnish that is applied topically to the teeth. It is an effective way to prevent tooth decay and should be used in conjunction with good oral hygiene practices.

**Correct Answer:** C.