Abnormally low levels of the neurotransmitter serotonin are associated with mania. disruptive mood dysregulation disorder. depression. bipolar disorder.

The correct option is: C. Depression

Explanation:

Major depressive disorder, also called depression, is a type of mental disorder which is characterized by low self esteem, lack of interests and energy, insomnia, psychosis, irritability, a feeling of worthlessness, helplessness, regret and hopelessness. A person suffering from depression may also experience delusions and hallucinations. Low levels of serotonin is associated with depression.    

konichiwa~! my name is zalgo and i am here to you out on this amazing day. i have been through break-ups before, and they are not easy. each one seems to get a bit harder yet easier. the best thing to do is do the things you enjoy doing the most before you had got in t he relationship. maybe even try and find new and more exciting things to do that will take your mind off of it. and it is no surprise you seem to have a fear to talk to anyone, most people do, it's called "anxiety". most people overcome and conquer their anxiety. just try talking to someone on a video game or go out to a coffee shop and try starting a conversation with a person. that will definitely !

i hope this ! : 3

"stay and stay proud! " - zalgo