Open type of blood vascular system and presence of haemocyanin pigment are the characters of :-

Options

A. Mollusca
B. Annelida
C. Echinodermata
D. Hemichordata

Answer

To solve the question about the open type of blood vascular system and the presence of hemocyanin pigment, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks which group of animals has an open type of blood vascular system and contains the pigment hemocyanin.

2. **Identify Key Terms**:
- **Open Type Blood Vascular System**: In this system, blood is not confined to blood vessels and can flow freely in the body cavity.
- **Hemocyanin**: This is a copper-containing protein that serves as an oxygen carrier in the blood of some invertebrates, functioning similarly to hemoglobin in vertebrates.

3. **Evaluate the Options**:
- **Option 1: Mollusca**: Mollusks are known to have an open circulatory system and contain hemocyanin as their oxygen-carrying pigment. This option seems correct.
- **Option 2: Annelida**: Annelids (like earthworms) have a closed circulatory system, which means this option is incorrect.
- **Option 3: Echinodermata**: Echinoderms have a water vascular system and do not contain hemocyanin. This option is also incorrect.
- **Option 4: Hemichordata**: While hemichordates have an open circulatory system, they do not possess hemocyanin. Thus, this option is incorrect as well.

4. **Conclusion**: Based on the analysis of each option, the correct answer is **Mollusca**, which has both an open type of blood vascular system and the presence of hemocyanin.

### Final Answer:
The correct answer is **Mollusca**.

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