Concussions are very serious injuries. Treatment of concussion involves monitoring and rest. Rest includes both physical and cognitive rest (including going easy on such activities as school work, television watching and text messaging). Symptoms usually go away entirely within three weeks, though they may persist, or complications may occur. People who have had one concussion seem to be more susceptible to another, especially if the new injury occurs before symptoms from the previous concussion have completely gone away. Repeated concussions may increase a person's risk in later life for dementia, Parkinson's disease, and/or depression. Although there is no cure for Parkinson's disease, it can be managed through surgery and/or medications. (Adapted from Wikipedia) Which sentence is unnecessary and could be eliminated without disturbing the flow and information of the paragraph? A) Concussions are very serious injuries. B) Although there is no cure for Parkinson's disease, it can be managed through surgery and/or medications. C) Repeated concussions may increase a person's risk in later life for dementia, Parkinson's disease, and/or depression. D) Rest includes both physical and cognitive rest (including going easy on such activities as school work, television watching and text messaging).