Circulatory system in birds is

Options

A. open type with haemoglobin in plasma
B. closed type with haemoglobin in RBCs
C. open type with haemoglobin in RBCs
D. closed type with haemoglobin in plasma

Answer

### Step-by-Step Text Solution:

1. **Understanding the Circulatory System**: The circulatory system in birds is classified as a closed circulatory system. This means that the blood is contained within blood vessels and is not free-flowing in the body cavity.

2. **Heart Structure**: Birds have a four-chambered heart, similar to mammals. This heart consists of two atria and two ventricles. The separation of chambers allows for efficient circulation of oxygenated and deoxygenated blood.

3. **Blood Flow**: In the closed circulatory system of birds, oxygenated blood and deoxygenated blood are kept separate. This separation is crucial for maintaining efficient oxygen delivery to tissues and organs.

4. **Presence of Hemoglobin**: In birds, hemoglobin is present in red blood cells (RBCs). Hemoglobin is the protein responsible for transporting oxygen from the lungs to the rest of the body.

5. **Conclusion**: Therefore, the correct description of the circulatory system in birds is that it is a closed type with hemoglobin present in red blood cells (RBCs).

### Final Answer:
The circulatory system in birds is a **closed type with hemoglobin in RBCs**.

---