The primary producers of the deep-sea hydrothermal vent ecosystem are:

Options

A. Blue-green alage
B. Coral reefs
C. Green algee
D. Chemosynthetic bacteria

Answer

### Step-by-Step Solution:

1. **Understanding Primary Producers**:
- Primary producers are organisms that can produce their own food through photosynthesis or chemosynthesis. They form the base of the food chain in an ecosystem.

2. **Identifying the Ecosystem**:
- The question refers to the deep-sea hydrothermal vent ecosystem. This environment is characterized by extreme conditions, including high pressure, darkness, and the absence of sunlight.

3. **Evaluating the Options**:
- **Blue-green algae**: These organisms require sunlight to perform photosynthesis, which is not available in the deep sea. Therefore, they cannot be primary producers in this ecosystem.
- **Coral reefs**: Corals are not primary producers; they are heterotrophic organisms that rely on other sources for food. Thus, this option is incorrect.
- **Green algae**: Similar to blue-green algae, green algae also require sunlight for photosynthesis, which is absent in deep-sea environments. Hence, they cannot be primary producers here.
- **Chemosynthetic bacteria**: These bacteria can produce their own food using chemical reactions, specifically by utilizing chemicals found in the hydrothermal vents, such as hydrogen sulfide. They do not rely on sunlight, making them suitable primary producers in this ecosystem.

4. **Conclusion**:
- The primary producers of the deep-sea hydrothermal vent ecosystem are **chemosynthetic bacteria**. They play a crucial role in this unique ecosystem by converting inorganic compounds into organic matter, supporting the food web.