Yes I believe it’s 4 explain for the others to see in understand
The phrase <em>the antique fire truck </em>is used as a complete subject, because you are including all of these words to form a subject, so it cannot be a simple one (just one word). It isn't a compound subject either, because that would be two or more words connected with a conjunction <em>and, </em>or some other one.
Answer:
to make sure no one has any negative dreams or feelings and to stop them early if they do
