**Core Concept**
Pit and fissure caries is a type of dental caries that occurs on the occlusal surfaces of teeth, particularly in the crevices and grooves. The primary causative organisms are bacteria that adhere to the tooth surface and feed on food particles, producing acid that demineralizes the enamel.

**Why the Correct Answer is Right**
The key organisms involved in pit and fissure caries are **Streptococcus mutans** and **Lactobacillus**. These bacteria have a unique ability to adhere to tooth surfaces using their glucosyltransferase enzymes, which synthesize sticky polysaccharides from glucose. This adherence allows them to colonize the tooth surface and feed on fermentable carbohydrates, producing acid that contributes to enamel demineralization. The acid production and adherence properties of these bacteria make them ideal candidates for causing pit and fissure caries.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect because while **Escherichia coli** is a common gut bacterium, it is not typically associated with dental caries. Its presence in the oral cavity is usually a result of contamination or other underlying conditions.

**Option B:**
This option is incorrect because **Acidophilus** is a genus of bacteria that is often used in probiotics and is generally beneficial to oral health. It is not typically associated with the production of acid or the development of dental caries.

**Option C:**
This option is incorrect because **Candida albicans** is a fungus that can cause oral infections, but it is not typically associated with the development of dental caries. Its presence in the oral cavity can be a result of other underlying conditions or immunocompromised states.

**Clinical Pearl / High-Yield Fact**
To prevent pit and fissure caries, it is essential to practice good oral hygiene, including regular brushing and flossing, and to use fluoride toothpaste. Additionally, the use of sealants on the occlusal surfaces of teeth can help prevent the adherence of bacteria and reduce the risk of caries.

**Correct Answer: C. Lactobacillus**