Answer:
A.Pulmonary artery
Explanation:
Generally,arteries are blood vessel that convey oxygenated blood away from the heart to the systemic circulation They are of wide diameter,and the walls are very thick.However,Pulmonary artery is different because it takes de-oxygenated blood from the heart(right atrium) to the lungs for pulmonary circulation.
The de-oxygenated blood undergoes oxygenation,with CO2 in it exchanged for the oxygen in the lungs.Thus oxygen diffused into the blood while C02 from the de-oxygenated blood diffused out though the nostrils to the environment.
Therefore the Pulmonary artery is needed for the pulmonary circulation to be initiated.The oxygenated blood enters the Left atrium. through the pulmonary veins (as the de-oxygenated blood enters the right atrium) ,and empties into the L.ventricle en route the aorta.
