## Core Concept
The question tests the knowledge of motility in various organisms, which is an essential characteristic in microbiology for identifying and classifying microorganisms. Motility refers to the ability of an organism to move independently using metabolic energy.

## Why the Correct Answer is Right
The correct answer, , is a non-motile organism. This classification is crucial in medical microbiology as it helps in the identification of the organism and in understanding its pathogenicity and interaction with the host.

## Why Each Wrong Option is Incorrect
* **Option A:** - This organism is motile, which makes it incorrect as the question asks for a non-motile organism.
* **Option B:** - This organism exhibits motility, hence it is not the correct answer.
* **Option C:** - This option is also motile, making it an incorrect choice.

## Clinical Pearl / High-Yield Fact
Remember that the ability or inability to move can be a critical feature for distinguishing between different species of bacteria. For instance, the presence or absence of flagella, which are the structures responsible for motility in bacteria, can be used as a diagnostic tool.

## Correct Answer: D.