Northern Company purchased a machine on January $1,2016,$ for $$120,000.$ At that time, the machine's useful life was an estimated six years with a zero salvage value. Just before depreciation was recorded for $2020,$ the machine's estimated useful life was extended six years beyond $2020$ with a $$8,000$ salvage value.

Using straight$-$line depreciation, what is the $2020$ depreciation expense?

A$)$ $$9,144$

B$)$ $$20,000$

C$)$ $$4,000$

D$)$ $$9,000$