The key idea is that bone strength determines whether a fall causes a fracture. Osteoporosis weakens bones by reducing bone mineral density and altering their microarchitecture, so even a low-energy fall can break them. In the elderly, this fragility makes fractures much more likely, especially in common sites like the hip, spine, and wrist. The other options don’t fit as risk-increasing factors here. Simply being older than 40 isn’t specific enough to predict fracture risk after a fall, and maintaining daily activity or a balanced diet helps protect bone health and reduce fracture risk rather than increase it.

When the diaphragm ruptures, a hole opens between the chest and abdominal cavities. Abdominal organs can herniate into the thorax, which reduces lung expansion and leads to difficulty breathing. At the same time, much of the abdominal contents move upward, so the abdomen may look sunken or hollow. This combination of respiratory distress and a sunken anterior abdominal wall is characteristic of diaphragmatic rupture after trauma. Spleen rupture would cause bleeding and shock signs rather than primary breathing difficulty. Aorta rupture leads to sudden, overwhelming hemorrhage. Stomach rupture typically causes peritonitis rather than the chest–lung symptoms described.

In tension pneumothorax, air builds up under pressure in the chest and pushes on the heart and great vessels, cutting off blood return to the heart. The only way to stop this deadly cycle is to relieve that pressure. Decompression of the injured side of the chest—such as needle thoracostomy followed by chest tube placement—immediately lets the trapped air escape, restores lung expansion, and improves venous return and cardiac output. Without relieving the pressure, other measures won’t halt the progression to death, even if they improve oxygen levels or support circulation for a short time. High-flow oxygen helps with oxygenation, but it doesn’t address the life-threatening pressure. Rapid IV fluids may temporarily support blood pressure but won’t relieve the mechanical compression. Bag-valve-mask ventilation can raise intrathoracic pressure and worsen the condition.

Secondary brain injury comes from the cascade of events that follow the initial head trauma, meaning the brain damage that occurs after the first impact as the body’s response and the brain’s own processes unfold. The statement that hypoxia (low oxygen) and hypotension (low blood pressure) are the two most common causes fits this idea because when the brain isn’t getting enough oxygen or enough blood flow, it cannot meet its energy demands. This leads to neuronal injury and can worsen the outcome by expanding the initial damage. Other options don’t capture this sequence. Signs of secondary injury aren’t typically immediate; they often emerge as the cascade progresses over minutes to hours. Cerebral edema is part of the secondary process, not something that defines primary injury—the initial impact is the primary injury, while edema develops afterward and can worsen secondary injury. And secondary injury does not arise from direct brain trauma alone; that direct damage is the primary injury caused by the impact itself.