Ans. A. Antegrade amnesia for more than 30 minutesExplanationThis question is directly adapted from a table in Love and Bailey, which mentions all indications of CT scan in case of head injuryNational Institute for Health and Clinical Excellence (NICE) guidelines for computed tomography (CT) in head injury.GCS <13 at any pointGCS 13 or 14 at 2 hoursFocal neurological deficitSuspected open, depressed or basal skull fractureMore than one episode of vomitingAny patient with a mild head injury over the age of 65 years or with a coagulopathy, for instance warfarin use, should be scanned urgentlyDangerous mechanism or injury or antegrade amnesia >30 minutes warrants CT within 8 hours