In which sentence is an essential appositive or appositive phrase underlined?

The book, Charlotte’s Web, was one of my favorite books as a child.

In the book Charlotte’s Web, Charlotte, a clever spider, finds a way to save her friend’s life.

Charlotte’s Web, a novel by E. B. White, portrays the powerful friendship between Wilbur and Charlotte.

The sentence "In the book Charlotte’s Web, Charlotte, a clever spider, finds a way to save her friend’s life." has an essential appositive "a clever spider" underlined.