Answer: A. Syphilitic

Explanation:
Luetic aortic aneurysm of tertiary syphilis:
Syphilis causes obliterative endarteritis of the vasa vasorum, which results in ischemia of the vessel’s media. The ischemia of the media leads to scarring and loss of elastic recoil, so the vessel dilates. Location is thoracic aorta (aortic root and arch).

Atherosclerosis is the most common cause of aneurysms, and such aneurysms most commonly occur in the abdominal aorta. Mycotic aneurysm occurs as a result of an infection from septic emboli or an aneurysm that has subsequently become infected.

Reference: Wyatt C., Kemp W.L., Moos P.J., Burns D.K., Brown T.G. (2008). Chapter 9. Vascular Pathology. In C. Wyatt, W.L. Kemp, P.J. Moos, D.K. Burns, T.G. Brown (Eds), Pathology: The Big Picture

Answer: C. Coarctation of the aorta

Explanation: You need to know that cystic hygromas (lymphatic malformations resembling hemangiomas) are a feature of Turner syndrome that later contributes to the better known “webbed neck.” Turner syndrome is also associated with coarctation of the aorta, and to a lesser extent, pulmonary stenosis.

Aneurysms involving the proximal aorta suggest tertiary syphilis. The clues given in a question about tertiary syphilis might be sexually transmitted disease or chronic
neurological signs.

Aortic dissection and cystic medial necrosis of the aorta would probably be presented in a question giving you a clue about Marfan’s syndrome, such as a patient with tall stature and hyperextensible joints.

Reference: Wyatt C., Kemp W.L., Moos P.J., Burns D.K., Brown T.G. (2008). Chapter 6. Genetic Disorders. In C. Wyatt, W.L. Kemp, P.J. Moos, D.K. Burns, T.G. Brown (Eds), Pathology: The Big Picture