Open circulatory system occurs in

Options

A. Earthworm
B. Snail
C. Cockroach
D. Both B and C.

Answer

To determine which organisms possess an open circulatory system, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Types of Circulatory Systems**:
- There are two main types of circulatory systems in animals: open and closed.
- In an open circulatory system, blood is not always contained within blood vessels and can flow freely through cavities, bathing the organs directly.
- In a closed circulatory system, blood is contained within vessels and is pumped around the body by a heart.

2. **Analyze the Options**:
- The question provides several options. We need to evaluate each one to determine if it has an open circulatory system.

3. **Option A: Earthworm**:
- Earthworms belong to the phylum Annelida.
- Annelids have a closed circulatory system.
- Therefore, earthworms do not have an open circulatory system.

4. **Option B: Snail**:
- Snails belong to the phylum Mollusca.
- Most mollusks, including snails, have an open circulatory system.
- Hence, snails do have an open circulatory system.

5. **Option C: Cockroach**:
- Cockroaches belong to the phylum Arthropoda.
- Arthropods, including cockroaches, also possess an open circulatory system.
- Thus, cockroaches have an open circulatory system.

6. **Conclusion**:
- Since both snails (Option B) and cockroaches (Option C) have an open circulatory system, the correct answer to the question is Option D: both B and C.

### Final Answer:
The open circulatory system occurs in both snails and cockroaches (Option D: both B and C).

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