What Is There About a Concussion That May Cause the Cognitive

Multiple Choice

What is there about a concussion that may cause the cognitive symptoms seen in some people following their injury? 

A) When you are unconscious, your brain is not getting enough nutrients, so the longer you are unconscious, the more apt you are to have problems. 
B) When you have a concussion, there is a very good probability that the brain is actually injured either by compression or some similar trauma. 
C) Concussions will not cause any problems unless you are unconscious for a while, which results in a loss of blood supply to the brain. 
D) Concussions will not cause cognitive problems unless the damage is accompanied by bleeding.