Kid had a viral URI then took aspirn -> Reye syndrome, a hepatic encephalopathy. There is increased ammonia production because of the liver damage, leading to hyperammonemia. This gets to the brain, is ocnverted to glutamine (an osmolyte). This causes the brain swelling.
It's not E) viral encephalitis because it implies the virus is directly causing the encephalitis. Instead, the viral infection -> aspirin -> liver damage -> ammonia -> crosses BBB -> converted to glutamine -> draws in water -> cerebral edema