Given a class Repetition： 
1. package utils； 
2. 
3. public class Repetition { 
4. public static String twice（String s） { return s + s； } 
5. } 
and given another class Demo： 
1. // insert code here
2. 
3. public class Demo { 
4. public static void main（String[] args） { 
5. System.out.println（twice（”pizza”））； 
6. } 
7. } 
Which code should be inserted at line 1 of Demo.java to compile and run Demo to print“pizzapizza”？（） 

Given a file GrizzlyBear.java： 
1. package animals.mammals； 
2. 
3. public class GrizzlyBear extends Bear { 
4. void hunt（） { 
5. Salmon s = findSalmon（）； 
6. s.consume（）； 
7. } 
8. } 
and another file， Salmon.java： 
1. package animals.fish；
2. 
3. public class Salmon extends Fish { 
4. void consume（） { /* do stuff */ } 
5. } 
Assume both classes are defined in the correct directories for theft packages， and that the Mammal class correctly defines the findSalmon（） method. Which two changes allow this code to compile correctly？（）