The kind of English you hear from newscasters. No slang, correct grammar, and full enunciation.
Just not the black newscasters, mind.
What are you talking about? Black newscasters are perfectly good at diction.
I don't see any indication this is true.
Which newscasters? They don't all sound the same to me. And where can I buy that book of "correct" grammar?
Very few professional newscasters use their normal speech patterns on the air. They deliberately train out regional dialects.
As for grammar, everybody who's been to high school in the US has had a grammar book that teaches correct (not "correct") grammar. There really is a right way and a wrong way.
Yes. There are definitely choices in word use but grammar is straightforward.