## **Core Concept**
The question tests the knowledge of enteric organisms, specifically their metabolic characteristics (anaerogenic) and physical properties (non-motile). Enteric organisms, also known as Enterobacteriaceae, are a large family of Gram-negative, facultatively anaerobic bacteria. Anaerogenic refers to the inability of these bacteria to produce gas (anaerobically) from carbohydrate fermentation.

## **Why the Correct Answer is Right**
Shigella species are known to be anaerogenic, meaning they do not produce gas from the fermentation of carbohydrates. They are also non-motile, which distinguishes them from some other enteric pathogens like Salmonella. Shigella's inability to produce gas and its non-motility are key characteristics used in its identification. This aligns with the description provided in the question.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While specific details about the organism are not provided, if we consider common enteric pathogens, *Escherichia coli* (E. coli) is generally motile and can be anaerogenic but is often used as a reference for gas production.
- **Option B:** Similarly, without specifics, if we think of *Salmonella*, it is usually motile, which does not fit the description.
- **Option C:** This option is not provided but based on common enteric bacteria, *Klebsiella* can be non-motile but is often associated with gas production.
- **Option D:** Given that the correct answer is , the other options must exhibit characteristics that do not match being both anaerogenic and non-motile.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that Shigella infections often cause dysentery, characterized by bloody diarrhea, fever, and abdominal cramps. The identification of Shigella in stool cultures can be facilitated by its non-motility and lack of gas production on fermentation media.

## **Correct Answer: C. Shigella.**