The only sentence which is not a proposition is Sit down, because this is imperative, you are ordering somebody to do something, whereas propositions merely inform.
The only sentence here with an infinitive phrase is the first one, and the infinitive phrase there is 'to write'. You ask the question - What did Christa choose? in order to find the object of that sentence, and the answer is 'to write'.
Larry should include the following two elements in his essay:
- An extensive summary of the plot
- Textual evidence to support the thesis
Hope this helps! Enjoy! :)
