Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

[EX Q]: an electronic book (also called an e-book, ebook or digital book) is a book in digital form.
[EX A]: e-book

[EX Q]: serie d is the top level of the non-professional football clubs in italy.
[EX A]: serie d

[EX Q]: lower silesian voivodeship is one of the 16 voivodeships of poland.
[EX A]:
lower silesian voivodeship