The answer to this question is #2
Insulin, as I am a diabetic I know this for whatever reason
The main symptom of anorexia is extreme weight loss
The answer to this question would be: <span>B. Receptor site
The receptor site of a neurotransmitter often only receives a specific kind of transmitter. That was because the receptor has a unique 3D structure, so different transmitter wouldn't fit into the receptor. That was similar to lock and key principles.</span>
