What happens to lovers when there are decreased levels of serotonin in the brain?

The serotonin is a chemical neurotransmitter in the brain responses to keep the "happy mood" in humans, so-called, the "the molecule of happiness". Low levels of serotonin may produce serious problems like depression, anxiety, memory low-self esteem, irritation and so on. When a lover has a low serotonin level in his brain, his mood and general behavior can be affected in great ways. Young people may not be aware of the great-negative consequences of the decreased levels of serotonin and a treatment should be carry out. Depression and anxiety can lead to terrible outcomes in someone's life.

1# the answer is c

2#the answer is a