A machine was purchased for Rs$.1,000$ and its life was estimated to be $3$ years and at the end of life its book value will be Rs$.512.$ If depreciation is calculated according to written down value method. The rate of depreciation would be:

A$\mathrm{.}25\%$

B$\mathrm{.}15\%$

C$\mathrm{.}20\%$

D$\mathrm{.}10\%$