I believe the answer mesolimbic dopamine:)
<span>A
monomaniac is a person who is a:
b. obsessed about
one single thing.</span>
I would say C, schizophrenia,
because schizophrenia is "a mental disorder that in many ways centers around not recognizing what is part of reality – namely, having psychotic breakdowns." It is not related to anxiety, as anxiety is classified as "neurotic" while schizophrenia is classified as "psychotic".