${?}_{{?}_{{?}_{?}}{?}_{{?}_{?}}{?}_{{?}_{?}}{?}_{{?}_{?}}{?}_{{?}_{?}}{?}_{{?}_{?}}{?}_{{?}_{?}}{?}_r\text{e}\text{f}\text{e}\text{r}\text{s}to\text{t}\text{o}\text{t}\text{a}\text{l}\text{i}\text{n}\text{v}\text{e}\text{s}\text{t}\text{m}\text{e}\text{n}\text{t}in\text{t}\text{h}\text{e}\text{c}\text{u}\text{r}\text{r}\text{e}\text{n}\text{t}\text{a}\text{s}\text{s}\text{e}\text{t}\text{s}\text{.}}$

$a.$

Net working capital

$b.$

Gross working capital

$c.$

Economic order quantity

$d.$

Permanent working capital