Answer
Zack should throw the book toward the back of the car shown by arrow number 3.
Work Step by Step
While the book is in the car, the book is moving with the same velocity as the car. In order for the book to land in the driveway, Zack must try to make the book's velocity vector point directly toward the driveway. From Zack's point of view in the car, Zack should throw the book back along the path shown by arrow number 3. Then the book's velocity vector relative to the ground should point directly toward the driveway.
