D. The conversation you write must sound natural for the characters.
More natural conversations between characters make your writing more fun to read. Reading a dialogue that sounds like it could actually happen engages the reader, and creates an investment in the characters themselves. Think of it this way, would you rather watch a movie with good acting or bad acting?
A central argument is a dominant and controlling argument.
A writer focuses on many things.
Some of them include:
Spelling
Capitalization
Punctuation marks
Topic
Number of paragraphs
And, the hook to grab the readers attention in the intro paragraph