A cow gives 20 liter 500 milliliter milk at a time. The calf drinks 1 liter 300 milliliter 900 milliliter milk is wasted by the milkman. How much milk is left with the milkman?

Question

$\begin{array}{11} (a)\; \text{19l 200ml} \\ (b)\; \text{18l 300ml} \\ (c)\; \text{18l 500ml} \\ (d)\; \text{19l} \end{array}$