Final answer:
The football player's loss of consciousness, confusion, and inability to recall what happened would support the suspicion of a concussion.
Step-by-step explanation:
Based on the information provided, the youth football player's loss of consciousness for about 3 minutes after being knocked to the ground is a clear indication of a possible concussion. Additionally, confusion and inability to recall what happened are also symptoms often associated with concussions. Therefore, both A) confusion and B) inability to recall what happened would provide support for the suspicion of a concussion in this case.