The correct answer is option 'B', Flagella.

Flagella are long, whip-like structures that protrude from the surface of prokaryotic cells and enable them to move. These structures are composed of a protein called flagellin. Prokaryotes can have one or multiple flagella, depending on the species and their mode of movement.

Flagella Structure:
- The flagellum consists of three main parts: the filament, the hook, and the basal body.
- The filament is the long, helical portion of the flagellum that extends outward from the cell. It is made up of many flagellin proteins arranged in a spiral pattern.
- The hook connects the filament to the basal body and allows for flexibility and rotation.
- The basal body is embedded in the cell membrane and is responsible for the rotation of the flagellum.

Flagella Movement:
- Prokaryotic cells use the rotation of the flagella to move in their environment.
- The basal body acts as a motor, utilizing energy from ATP to rotate the flagellum.
- The rotation of the flagella creates a whip-like motion, propelling the cell forward.
- By controlling the direction and speed of flagellar rotation, prokaryotic cells can move towards or away from certain stimuli, such as light or chemical gradients.

Advantages of Flagella:
- Flagella allow prokaryotic cells to move towards favorable conditions, such as nutrients or light, and away from harmful substances or unfavorable environments.
- They enable prokaryotes to explore their surroundings and find suitable habitats for growth and survival.
- Flagella also play a role in the colonization of host organisms by pathogenic bacteria, allowing them to move within tissues and evade the host immune system.

In conclusion, flagella are important structures that enable prokaryotic cells to move. They provide motility, allowing cells to navigate their environment and respond to stimuli. Understanding the structure and function of flagella is crucial for studying the behavior and characteristics of prokaryotic organisms.