Final answer:
The patient's symptoms and assessment findings after a car crash, including double vision, ovoid pupil, and reduced Glasgow Coma Score, are indicative of increased intracranial pressure likely due to a subdural hematoma.
Step-by-step explanation:
If a patient was involved in a car crash, is experiencing a severe headache, nausea, vomiting, diplopia, has an ovoid pupil, and a Glasgow Coma Score of 10, these symptoms and assessment findings might suggest a significant intracranial injury. The symptoms such as diplopia, which is double vision, and the presentation of an ovoid pupil are indicative of increased intracranial pressure, which can be caused by bleeding within the cranial vault. Given the mechanism of injury (a car crash) and the neurological signs, the most likely diagnosis from the options provided would be a subdural hematoma (option b), which is a collection of blood between the dura mater and the brain that can compress brain tissue and cause these types of symptoms.