An insect circulatory system is best described as:

Options

A. totally closed like ours, with arteries and veins
B. similar to ours with general closed vessels but no distinct arteries and veins
C. an open system that mostly washes "blood" through the body cavities
D. totally absent, each body cell manages on its own to gain food and get rid of wastes

Explanation

To answer the question "An insect circulatory system is best described as:", we need to understand the characteristics of the circulatory system in insects.

### Step-by-Step Solution:

1. **Identify the Type of Circulatory System**: Insects possess an open circulatory system. This means that their blood (hemolymph) is not entirely contained within blood vessels.

2. **Understanding Open Circulatory System**: In an open circulatory system, the heart pumps hemolymph into the hemocoel (the body cavity), where it bathes the organs directly. This is in contrast to a closed circulatory system, where blood is contained within vessels.

3. **Components of Insect Circulatory System**: The main components include:
- A dorsal heart that pumps hemolymph.
- Hemolymph that circulates through the body cavity.
- Ostia (small openings) in the heart that allow hemolymph to enter the heart after it has circulated through the body.

4. **Function of the Circulatory System**: The primary function of the insect circulatory system is to transport nutrients, hormones, and waste products. However, it does not transport oxygen as insects have a separate respiratory system (tracheal system) for that purpose.

5. **Conclusion**: Therefore, the insect circulatory system can be best described as an open circulatory system, where hemolymph is pumped into the body cavity and directly bathes the organs.

### Final Answer:
An insect circulatory system is best described as an **open circulatory system**.

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