A 19-year-old hockey player sustains a concussion during a game. He had brief confusion but no loss of consciousness, and CT is normal. According to Canadian paediatric concussion guidelines, when should he return to full-contact play?AImmediately once CT is normalBAfter 24 hours symptom-free, regardless of step-wise progressionCAfter a graded return-to-play protocol once he is completely symptom-free at rest and with exertionDOnly after 6 months, regardless of symptomsENever; contact sport is permanently contraindicated after a single concussionCheck my answer