In my opinion, the correct answer is A. <span>It is the predicate of the sentence. The verb phrase in this sentence is "are invited to stay". It is a phrase and not just a regular verb because it has its own modifier ("to stay") that describes or completes it, providing additional information. This predicate is in passive voice because the subject is actually the one that undergoes the action (instead of doing it, as subjects normally do), whereas the agent (the one who actually does the action) is unmentioned here.</span>
