Slope of counter$-$current flow rotary drier is in the range of $\_\_\_\_\_\_\_\_\_$ meter$/$metre$.$

$0$ to $0\mathrm{.}08$

$0$ to $0\mathrm{.}8$

$0$ to $1\mathrm{.}5$

$0$ to $2\mathrm{.}2$