The central idea/thesis in your informative speech should follow all of the guidelines below except: audience link to the topic of the speech (establishing common ground) at least two different kinds of support materials. speaker’s credibility and/or link to the topic of the speech central idea/thesis sentence previewing the main points of the speech attention getting technique

The central idea/thesis in an informative speech should include all the guidelines mentioned except option 2) “At least two different kinds of support materials.” When delivering a speech you don’t need to include several support material such as videos, power point presentations and other visual or audio aids.

The important point when giving a speech is to make sure that your audience understands or is related to the topic you are about to talk about. Besides, it is very important that you have credibility as orator either because you know about the topic or because your audience believes you are knowledgeable to talk about a certain issue.  

Also, your central idea sentence should provide the audience hints and a forecast of the main ideas that will be developed during the speech.  

And finally, it is essential that you apply certain attention techniques so that your audience gets involved in the speech. You can call the audience’s attention by bringing examples or telling anecdotes that illustrate your speech.

tree and the cat in the tree

very interesting story but where is the question what is actually a question i don't understand