If you suspect that a person has suffered a concussion, the appropriate actions to take are:
c) Have the person stop all activity and follow up with a qualified healthcare provider as soon as possible.
It's important to allow the person to rest and seek professional medical evaluation to ensure proper care and management of their condition. Options a) and b) may be relevant in specific situations, but the priority should be to have the person cease any activities and consult a healthcare professional. Option d) should be avoided, as returning to normal activities too soon can pose significant risks.