A closed circulatory system is found in :

Options

A. insects
B. snails
C. earthworms
D. scorpions

Explanation

To determine which organism has a closed circulatory system, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding Closed Circulatory System**:
- A closed circulatory system is characterized by blood that circulates within a network of vessels (arteries and veins). This allows for more efficient transport of nutrients and oxygen to organs.

2. **Analyzing the Options**:
- **Option 1: Insects**
- Insects belong to the phylum Arthropoda. They possess an open circulatory system where blood (hemolymph) flows freely in the body cavity and does not circulate through a closed network of vessels. Thus, insects do not have a closed circulatory system.

- **Option 2: Snails**
- Snails belong to the phylum Mollusca. They also have an open circulatory system, where blood is not confined to vessels but rather bathes the organs directly. Therefore, snails do not have a closed circulatory system.

- **Option 3: Earthworms**
- Earthworms belong to the phylum Annelida. They have a closed circulatory system, where blood is contained within vessels. Earthworms possess five pairs of aortic arches that function similarly to a heart, pumping blood through a network of vessels. Thus, earthworms do have a closed circulatory system.

- **Option 4: Scorpions**
- Scorpions, like insects, belong to the phylum Arthropoda. They also have an open circulatory system, similar to insects, where the blood is not contained within vessels. Therefore, scorpions do not have a closed circulatory system.

3. **Conclusion**:
- After analyzing all the options, the only organism that possesses a closed circulatory system is **earthworms**.

### Final Answer:
A closed circulatory system is found in **earthworms**.

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