It illustrates the placement of materials to make the sequence of tasks clear- in this way the diagram support the purpose of the document.
Option: A
Step-by-step explanation:
Diagram is used to give support to the document. It also fulfill the purpose of the documents because documents alone can not clarify the things in better way that with attached diagram it can. Form a supporting diagram one can easily draw a mind map of the fact then after going through the text will be much helper in clear understanding.
Purpose of the documents made clear almost by the diagram. After going through the diagram text description stands much bold to the reader. In this way supporting diagram hepls in illustration of documents.