Short Answer B<<<<====
If you think it is D, then pretty soon you will be in a rut, unless these characters meet other characters. Then it's fine. Series of novels written by women quite commonly do this. The main character of one novel will become a minor character in another.
Never restrict your language. It is just about the worst thing you can do.
Punctuation is a very minor part of writing style. Be sure and use standard punctuation. Punctuation always aids a reader. Weird punctuation is not a good idea.
We're left with reading expert authors. You want to do this to allow yourself to appreciate what you are reading. Good language flows and good characters handled by experts become our friends and guides while we read about them. The more you appreciate good writing, the more you will want to find your own voice.
