During fieldwork on a factory's industrial system, the linkages between raw material inputs, production processes and outputs are best presented in a report using which type of diagram?

A systems (flow) diagram with labelled arrows is the standard way to show how inputs, processes and outputs are linked in an industrial system, since it makes the flow of materials and energy through the factory visible to a reader. A choropleth map, pie chart or scatter graph are suited to showing spatial variation, proportions or a relationship between two variables instead, not process linkages within a single system.