Which of the following is true?

There isn't a proper or improper way of using casual$/$daily speech $($ex: ain't$).$ This demonstrates that language is the proper version written down in grammar books$/$dictionaries$.$

There isn't a proper or improper way of using casual$/$daily speech $($ex: ain't$).$ This demonstrates that language is NOT the proper version written down in grammar books$/$dictionaries$,$ but rather what is actually in the speakers' heads.

There is a proper and improper way of using casual$/$daily speech $($ex: ain't$).$ This demonstrates that language is the proper version written down in grammar books$/$dictionaries$.$

There is a proper and improper way of using casual$/$daily speech $($ex: ain't$).$ This demonstrates that language is NOT the proper version written down in grammar books$/$dictionaries$,$ but rather what is actually in the speakers' heads.