Answer: I think im going to go with Option 2 because of Cycling .
First is the brain, spinal cord, and heart begin to develop. Then A blood vessel forms which will later develop into the heart and circulatory system.
Answer:
Aorta, Pulmonary artery, left atrium, mitral valve, aortic valve, left ventricle, right atrium, tricuspid valve, and right ventricle Hopefully this helps!
