The knife, because its a knife
The adrenal gland releases adrenaline
Exhaustion would be a key answer to this but they're others if needed.
Autism Spectrum Disorder, I say this because, even though the child is high functioning in other areas, they still have the previous diagnosis of Asperger's, which now in the DSM-5 since 2013, is just considered Autism Spectrum Disorder.
