The answer is to discuss the speech he is making. Hope this helps.
Expository text gets to the point rather quickly. It is intended as education rather than just narrative text. An example of narrative text is the Excerpt by Charles Dickens which is meant to draw a picture of what this woman was like.
So the last one is out.
The first one talks about volcanoes and how they are classified. That's one of your answers if you are trying for brevety and education.
I think the second one would also be a choice. It is trying to show you the nature of anxiety and what causes it. You learn a lot about symptoms from reading it. It's quick and to the point. Expository? Yes.
I don't think four is exactly expository, but I might be wrong. It sounds too argumentative to be completely expository. It wouldn't be my first choice even though I have read Twain a great deal, beginning in my teens. He always has something pointedly funny to say about the human condition. So it's hard for me not to include him in anything. It's not exactly narrative either. The tough ones are three and four.
Three tries to tell you what it would be like to live in another country. I think it likely is the choice you are looking for.
Answers 1,23. I could be wrong, so if you have a different answer in mind, go with it.
