Voracious means having a very great appetite, eating large amounts of food, or desiring something in a very large amount. A voracious reader, for example, reads a huge number of books.
Ravenous also means extremely hungry, so it is the closest match in meaning.
Tenacious means holding firmly to something, truthful means honest, and spacious means having a lot of room. None of these match voracious.
So the answer is option D, Ravenous.