This can be different for each person you ask
one reason is you can play the book out how you want to, imagine the characters your way, what the place looks like, etc. With a movie that is taken away from you. You are told how everything looks, and the movie/TV van leave out many stuff from the book
The answer is drafting so it is c
Answer: the 4 factors of fair use
The purpose and character of the use, including whether such use is of commercial nature or is for nonprofit educational purposes. ...
The nature of the copyrighted work. ...
The amount and substantiality of the portion used in relation to the copyrighted work as a whole.
The effect of the use upon the potential market for, or value of, the copyrighted work
