Answer: D - Uncontrolled hemorrhage is the most common cause of fatality in a blast injury, around 80%, many of them preventable. This demonstrates the importance of stopping uncontrolled bleeding. The other choices are less common causes of fatality in blasts. Isolated concussive injuries, such as might cause closed head injuries or tension pneumothorax, are not as common as severe as injuries from flying shrapnel and other fragments. These injuries are usually not localized to any particular region and can cause hemorrhage or soft tissue damage in any location, so a proper primary and secondary trauma survey is critical.