The ventricle of frog opens into 

Options

A. sinus venosus
B. Conus arteriosus
C. aortic arch
D. vena cavae

Answer

To answer the question "The ventricle of frog opens into," we can break down the solution into the following steps:

### Step-by-Step Solution:

1. **Understanding the Structure of Frog's Heart**:
- Frogs have a three-chambered heart, which consists of two atria (or auricles) and one ventricle. This unique structure is important for understanding how blood flows through the heart.

2. **Identifying the Function of the Ventricle**:
- The ventricle is a muscular chamber responsible for pumping blood out of the heart and into the circulatory system.

3. **Identifying the Opening of the Ventricle**:
- In frogs, the ventricle opens into a structure known as the **conus arteriosus**. This is a sac-like structure located on the ventral side of the heart.

4. **Evaluating the Other Options**:
- **Sinus venosus**: This is a chamber that collects deoxygenated blood from the body but does not connect to the ventricle.
- **Aortic arch**: This is part of the main artery that carries blood away from the heart, not where the ventricle opens.
- **Vena cava**: These are large veins that return deoxygenated blood to the heart, specifically into the atrium, not the ventricle.

5. **Conclusion**:
- Therefore, the correct answer is that the ventricle of the frog opens into the **conus arteriosus**.

### Final Answer:
The ventricle of the frog opens into the **conus arteriosus**.