Classify the Following Costs as Direct, Indirect, or Neither

Classify the following costs as direct, indirect, or neither: $$\begin{array} { | l | l | } \hline \text { a) } & \text { labor for machine maintenance } \\\hline \text { b) } & \text { factory equipment depreciation } \\\hline \text { c) } & \text { materials not traceable to specific products } \\\hline \text { d) } & \text { office equipment depreciation } \\\hline \text { e) } & \text { materials traceable to specific products } \\\hline \text { f) } & \text { insurance expired on admini strative facilities } \\\hline \text { g) } & \text { product assembly labor incurred } \\\hline \text { h) } & \text { administrative office salaries } \\\hline \text { i) } & \text { salespersons' salaries } \\\hline \text { j) } & \text { utilities on factory building } \\\hline \text { k) } & \text { putilities on administrative facilities } \\\hline\end{array}$$