9. Which of the following statements about polymorphism are true? (Choose all that apply) An object may be cast to a subtype without an explicit cast. If the type of a method argument is an interface, then a reference variable that implements the interface may be passed to the method. A method that takes a parameter with type java.lang.Object can be passed any variable. All cast exceptions can be detected at compile-time. By defining a final instance method in the superclass, you guarantee that the specific method will be called in the parent class at runtime. Polymorphism applies only to classes, not interfaces. 10. Which of these classes compile and will include a default constructor created by the compiler? (Choose all that apply) public class Bird \{\} public class Bird \{ public bird() ff \} public class Bird { public bird(String name) \{\}} public class Bird \{ public Bird() }}} public class Bird { Bird(String name) \{\}} public class Bird { private Bird(int age) \{\}} public class Bird { public Bird bird() \{return null; }} 11. Which statements about polymorphism and method inheritance are correct? (Choose all that apply) It cannot be determined until runtime which overridden method will be executed in a parent class. It cannot be determined until runtime which hidden method will be executed in a par- ent class. Marking a method static prevents it from being overridden or hidden. Marking a method final prevents it from being overridden or hidden. The reference type of the variable determines which overridden method will be called at runtime. The reference type of the variable determines which hidden method will be called at runtime. 12. Which of the following statements about abstract class are true? (Choose all that apply) Abstract class is a hybrid of concrete class and abstract interfaces. Abstract class can be initiated itself. Abstract class cannot have attributes. Abstract method is only allowed to be in abstract class. Abstract method must be implemented. Abstract class can extend from a superclass and implement multiple interfaces