In which situation below should you insert a comma?

a$.$ In between an independent clause and a dependent adverb clause that follows it$.$

b$.$ Before a coordinating conjunction that links two clauses, where the second clause has a stated subject.

c$.$ Before the last phrase in a series of lengthy phrases

d$.$ Before the last item in a series of items

e$.($a$)$ and $($b$)$

f$.($b$)$ and $($c$)$

g$.($c$)$ and $($d$)$