A compile-time error occurs because obj1 is declared as type C1 but instantiated as type C2. A compile-time error occurs because obj1 is declared as type C1 but instantiated as type C2 . A A runtime error occurs because method m1 does not appear in C2. A runtime error occurs because method m1 does not appear in C2 . B Method m1 is not executed because it does not appear in C2. Method m1 is not executed because it does not appear in C2 . C Method m2 is executed from the subclass instead of the superclass because obj1 is instantiated as a C2 object. Method m2 is executed from the subclass instead of the superclass because obj1 is instantiated as a C2 object. D Method m2 is executed twice (once in the subclass and once in the superclass) because it appears in both classes.