The correct answer is A) graphics and visual images.
Procedural documents include graphics and visual images to help the reader understand concepts that might be difficult to properly explain just using words.
A procedural document is one that explains or outline the step by step of a procedure, a list, a system, or a registration. In order to have a full and clear procedural document, the writer can and headlines or subheadlines. But if the writer wants to exemplify and help the reader understand concepts that might be difficult to properly explain just using words, he needs to include graphics and visual images.