18) Assume we have a class called Dog and we are creating objects of that class. Dog class has the private instance variables name, age, and height as well as a mutator method called setDog to give them values (in that order). What is wrong with the following code? public class DogDemo{ public static void main(String[] args) { Dog D1; Dog D2; D1.setDog("Rin tin tin", 12, 24); D2.setDog("Jake", 28, 26); } } 19) Can you reference an instance variable by name within the definition of a static method without using a class name and a dot? Explain your answer. 20) Can you invoke a non-static method within a static method? Explain. 21) In chapter 5 listing 5.19 (you should have this in your email) there is the class Species. It contains a method called setSpecies that sets name, population and growth rate. Could this class have another method called setSpecies that has only one parameter for the name of the species and that sets both the population and growth rate to 0? If you can what would the code for this method look like