Mohr Company purchases a machine at the beginning of the year at a cost of $$24,000.$ The machine is depreciated using the double$-$declining$-$balance method. The machine's useful life is estimated to be $5$ years with a $$4,000$ salvage value. The machine's book value at the end of year $2$ is:

Select one:

a$.$ $$12,000.$

b$.$ $$7,200.$

c$.$ $$9,600.$

d$.$ $$8,640.$

e$.$ $$14,400.$