Which of the following best describes indented bill of materials?

Question $9$ options:

a$)$ Indented bill of materials lists the parts used for production.

b$)$ Indented bill of materials only highlights parts and components that should be bought.

c$)$ Indented bill of materials shows the hierarchy of parts and components.

d$)$ Indented bill of materials shows the relationship between sub$-$assemblies and assemblies.