This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Write down what an abstract method is for, and it should become obvious why it cannot have a private modifier (not “specifier”).
Work out what private and protected mean and try to work out what they would mean for top‑level classes. then you can see why the only access modifier permissible for a top‑level class is public.