<prompt> Most common cause of abdominal aortic aneurysm isAtherosclerosisSyphilisMarfans syndromeEhlers-Danlos syndrome  <response>: A Atherosclerosis ABDOMINAL AORTIC ANEURYSMS: Abdominal aortic aneurysms occur more frequently in males than in females, and the incidence increases with age. Abdominal aortic aneurysms may affect 1 to 2 of men older than 50 years. At least 90 of all abdominal aortic aneurysms 4.0 cm are affected by atherosclerosis, and most of these aneurysms are below the level of the renal arteries. Prognosis is related to both the size of the aneurysm and the severity of coexisting coronary artery and cerebrovascular disease. The risk of rupture increases with the size of the aneurysm. 