$6.$ A company bought a new machine for $$100,000$ on January $1.$ The machine is expected to last five years and has a residual value of $$10,000.$ If the company uses the double declining$-$balance method, book value at the end of year $2$ will be

A$.$ $$12,800$

B$.$ $$60,000$

C$.$ $$36,000$

D$.$ None of the above.