A young man with Marfan syndrome presents to the emergency department with sudden, sharp chest pain radiating to the back. Imaging studies reveal an intimal flap in the ascending aorta and a false lumen with differential flow. Which of the following histologic features of the aortic wall most likely predisposed this patient to the described condition?

a. Thickening of the tunica intima due to increased collagen
b. Overgrowth of smooth muscle cells in the tunica media
c. Calcification of the tunica externa
d. Thinning of the tunica media due to reduced elastin fibers