Which of the Following Alternatives Best Represents the Sequence of Events

Which of the following alternatives best represents the sequence of events by which melatonin is secreted in the blood

A) pituitary gland + pineal gland $\rightarrow$ melatonin
B) pineal gland $\rightarrow$ suprachiasmatic nucleus $\rightarrow$ melatonin
C) suprachiasmatic nucleus + pineal gland $\rightarrow$ melatonin
D) suprachiasmatic nucleus $\rightarrow$ pineal gland $\rightarrow$ melatonin