static char getOption() {
        System.out.print("\tChoose action: ");
        System.out.print("(1) students at a school, ");
        System.out.print("(2) shortest intro chain, ");
        System.out.print("(3) cliques at school, ");
        System.out.print("(4) connectors, ");
        System.out.print("(q)uit? => ");
        char response = stdin.next().toLowerCase().charAt(0);

        while (response != '1' && response != '2' && response != '3' && response != '4' && response != 'q') {
            System.out.print("\tYou must enter one of 1, 2, 3, 4, or q => ");
            response = stdin.next().toLowerCase().charAt(0);
        }
        return response;
    }