The bacterial flagellum has

Options

A. a basal granule
B. a hook
C. a main filament
D. all of these

Answer

### Step-by-Step Solution:

1. **Understanding the Structure of Bacterial Flagellum**:
The bacterial flagellum is a complex structure that consists of three main parts: the basal body (or basal granule), the hook, and the main filament.

2. **Identifying the Parts**:
- **Basal Body (Basal Granule)**: This part anchors the flagellum to the bacterial cell wall and membrane. It allows for rotation, enabling the flagellum to move.
- **Hook**: This is a curved structure that connects the basal body to the filament. It serves as a flexible joint, allowing the filament to rotate.
- **Main Filament**: This is the long, whip-like structure that extends from the hook. It is responsible for the actual movement of the bacterium.

3. **Function of Each Part**:
- The **basal body** allows for 360-degree rotation, which is essential for the movement of the bacterium.
- The **hook** transmits the rotational motion from the basal body to the filament.
- The **main filament** moves in a whip-like manner, propelling the bacterium forward.

4. **Conclusion**:
Since the bacterial flagellum consists of all three parts (basal body, hook, and main filament), the correct answer to the question is "all of these."

### Final Answer:
The bacterial flagellum has a basal granule, a hook, and a main filament. Therefore, the answer is **all of these**.

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