Identify the organ according to the function and choose the answer correctly:
1. 
The diagram shows a human heart. Which number represents the valve between left ventricle and aorta?
2. 
The diagram shows the flow of blood in the heart. Which labelled part carries blood from lungs to heart?
3. 
The diagram shows the circulation of blood from heart to various parts of the body. Which of the following shows the return of oxygenated blood from the lungs to the left atrium?