Answer the following question given this paragraph: 

Blood flows in only one direction in the heart. Blood enters the atria, which contract and push blood into the ventricles. The atria relax and the ventricles fill with blood. Finally, the ventricles contract and push blood around the body.


Q: Blood enters the heart in what valve?

 Choices:

- tricuspid

- aortic

- mitral

- atria

A:
atria
