Imposing visible structure is achieved by all of the following EXCEPT:Group of answer choicesenumeratingtransitionsinformative headingsclustering information

The question is asking which of the given options is NOT a method of imposing visible structure. Let's go through each option:

1. Enumerating: This is a method of imposing visible structure. It involves numbering or listing items or points in a certain order to make the information more organized and easier to understand.

2. Transitions: These are also used to impose visible structure. Transitions are words or phrases that help to make a piece of writing flow better, by creating links between different ideas or sections.

3. Informative headings: These are definitely a way of imposing visible structure. Headings are used to divide a piece of writing into sections, each of which deals with a different topic or aspect of the overall subject. They give the reader an idea of what each section is about before they start reading it.

4. Clustering information: This is also a method of imposing visible structure. It involves grouping related pieces of information together, which makes it easier for the reader to understand the relationships between different pieces of information.

So, all of the options given are actually methods of imposing visible structure. Therefore, the question seems to have no correct answer as it stands.