What is the result？（）

单项选择题What is the result？（）

A.Compilation fails due to an error in line 23.
B.Compilation fails due to an error in line 29.
C.A ClassCastException occurs in line 29.
D.A ClassCastException occurs in line 31.
E.The value of all four objects prints in natural order.

单项选择题Which method will complete this class？（）

A.public int compareTo（Object o）{/* more code here */}
B.public int compareTo（Score other）{/* more code here */}
C.public int compare（Score s1， Score s2）{/* more code here */}
D.public int compare（Object o1， Object o2）{/* more code here */}

单项选择题Which statement is true？（）

A.The equals method does NOT properly override the Object.equals method.
B.Compilation fails because the private attribute p.name cannot be accessed in line 5.
C.To work correctly with hash-based data structures， this class must also implement the hashCode method.
D.When adding Person objects to a java.util.Set collection， the equals method in line 4 will prevent duplicates.

单项选择题Which change can you make to Target without affecting Client？（）

A.Line 4 of class Target can be changed to return i++；
B.Line 2 of class Target can be changed to private int i = 1；
C.Line 3 of class Target can be changed to private int addOne（）{}；
D.Line 2 of class Target can be changed to private Integer i = 0；

单项选择题What is the result？（）

A.0
B.1
C.4
D.Compilation fails.
E.An exception is thrown at runtime.