Due to decelerations, aorta can be ruptured at places where it is fixed except:

Ans is 'b' i.e. Behind the esophagus "The majority of blunt injuries to the thoracic aorta occur at aortic isthmus just distal to the left subclavian artery. Other locations include the transverse arch, proximal ascending aorta, and descending aorta just proximal to the diaphragm." - Sevitt S. The mechanisms of traumatic rupture of the thoracic aorta. Br J Surg 1977; 64:166About 'aortic valves' the following reputed radiology website writes:"The above figures represent the site of injury in those patients who present to hospital. The ascending aorta is injured in 20 to 25% of cases at autopsy but most of these patients die at the scene from serious complications such as a ruptured aortic valve, coronary artery laceration or hemopericardium with pericardial tamponade. "Aortic isthmus is portion of the proximal descending thoracic aorta between the left subclavian artery origin and the ligamentum arteriosum. Tethering of the aorta by the ligamentum arteriosum is believed to account for the high frequency of aortic injury in the isthmus region. The isthmus is thought to be a transition zone between the more mobile ascending aorta and arch and the relatively fixed descending thoracic aorta which allows for stretching with rapid deceleration