Final answer:
A clear fluid leaking out of the ear after a car accident indicates a basilar skull fracture, which is a serious injury to the head.
Step-by-step explanation:
When you arrive at a motor accident scene and notice a man whom a car has hit has clear fluid leaking out of his ear, the fluid is likely cerebrospinal fluid. This indicates that the patient has likely suffered from a basilar skull fracture. Basilar skull fractures can be life-threatening as they can damage the artery that passes through the carotid canal.