The correct answer is A. relevant.
The word “extraneous” means “not essential or relevant.” In the context of the question, the four chapters are not essential to the structure of the book. They may be interesting or informative, but they do not contribute to the main argument or story of the book.
The word “integral” means “essential or necessary.” In the context of the question, the four chapters are not essential to the structure of the book. They may be interesting or informative, but they do not contribute to the main argument or story of the book.
The word “important” means “having great significance or value.” In the context of the question, the four chapters are not important to the structure of the book. They may be interesting or informative, but they do not contribute to the main argument or story of the book.
The word “needful” means “required or necessary.” In the context of the question, the four chapters are not needful to the structure of the book. They may be interesting or informative, but they do not contribute to the main argument or story of the book.