I'd say B, seems most likely . Hope that helps
I agree with the other person, the other sentences are not complete. so in turn it must be: Wagon trains might include 100 wagons.
maybe
Google is a search engine that finds information that is related to the specific topic of what you are searching.
Subject directory is a classified web pages in an organized set of categories.
Can you put a picture or something so I can help with the question