Jane is concerned that her friend has been diagnosed with depression. Which is the best answer? Responses Jane’s friend may have a decrease in brain serotonin activity, which can result in depression. Jane’s friend may have a decrease in brain serotonin activity, which can result in depression. Jane’s friend has serotonin, as all people and animals do. It plays a role in the central nervous system. Jane’s friend has serotonin, as all people and animals do. It plays a role in the central nervous system. Low levels of serotonin are linked with depression. Low levels of serotonin are linked with depression. Serotonin is an organic compound formed from tryptophan. It is a neurotransmitter. Serotonin is an organic compound formed from tryptophan. It is a neurotransmitter. Serotonin plays a role in sleep, blood clotting, sexual function, and how good a person