The aorta is the vessel that delivers oxygenated blood to systemic capillaries for gas exchange.
The pulmonary trunk carries unoxygenated blood so it is out of the question. The circumflex artery is a branch of the left coronary artery which supply blood to the heart. This leaves us with the AORTA.
This is most likely due to the fact that people with AIDS have supressed immune systems. Those with AIDS suffer from a suppressed immune system, making it much more likely for them to catch illnesses and increasing the severity of the affliction.
