When separating items in list, a writer should?

Question: When separating items in list, a writer should?

(1)Writer add a comma before the “and” before the last item.

(2)end the list with a colon.

(3)add a comma after the “and” before the last item

(4) None of these.

Answer (1) is absolutely right answer because we know that  When separating items in list,a writer should is Writer add a comma before the “and” before the last item.