What are the speakers mainly talking about?

Listen to the conversation.
Then read the four choices marked A， B， C and D, and decide which is the best answer according to what you hear.
M： British English and American English are really about the same, aren’t they?
W： I don’t think so. It seems to me that some of the spellings are different. Words like “theater” and “center” end in r-e in England instead of in e-r like we spell them. There are more examples, like the word “color”. In fact, many words that end in o-r in American English are spelled o-u-r in British English.
M： I’m still not convinced. I mean, if someone comes here from England, we can all understand what he’s saying. The spelling doesn’t really matter that much.
W： Okay. Are we just talking about spelling? Are there any differences in pronunciation and meaning too？
M： Well, in fact I remember seeing an English movie where the actors kept calling their apartment a flat. Half of the movie was over before I realized what they were talking about. So there are slight differences in spelling and some vocabulary.
W： And pronunciation, too. You aren’t going to tell me that you sound like Richard Burton.
M： Richard Burton’s English.
W： Okay. Anyway, the pronunciation is different. I think what we’re really disagreeing about is the extent of the difference. We all agree that British English and American English are a little different, right?
M： Sure.