The artery carrying blood from the right ventricel of the heart to the lungs for oxygenation A. Pulmonary artery
B. Aorta
C. Right Atrium
D. Right Ventricle

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.

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.