A company purchased equipment for $$50,000.$ The equipment has a useful life of $10$ years and a residual value of $$5,000.$ Using the straight$-$line method, what is the annual depreciation expense?

$$ A$)$ $$4,500$

$$ B$)$ $$5,000$

$$ C$)$ $$4,000$

$$ D$)$ $$4,750$