In a vehicle mileage application, you enter number of miles traveled by a vehicle and the amount of fuel used for 30 consecutive days. From this data the average monthly mileage of the vehicle is calculated. Which of the following should be done to improve the program design? The next time the average monthly mileage is calculated, use copy and paste to avoid making coding errors. Consider writing a method that returns void. Consider writing a method that returns the average monthly mileage as a double value. Provide the same comment every time you repeat the average monthly mileage calculation. Which of the following is the correct header for a greaterThan method definition that takes two arguments of type double and returns true if the first value is greater than the second value? public static int greaterThan (double a, double b) public static boolean greaterThan(double a, double b) public static double greaterThan(boolean a, boolean b) public static boolean greaterThan (double a, b)