Explanation:

- The book 'The Best Thing About You is You' is authored by the well-known Indian actor Anupam Kher.

- Anupam Kher, a veteran in the Indian film industry, has also explored other creative avenues such as writing.

- Amitabh Bachchan, another legendary actor, is not associated with this book. He is recognized for his extensive contributions to Indian cinema.

- Anil Kapoor, famous for his versatile roles across various films, has not penned this book either.

- Annu Kapoor is also an actor but has no relation to the authorship of this book.

Option 3: Anupam Kher is the correct answer.