class One { <br />  public One foo() { return this; } <br /> } <br /> class Two extends One { <br /> public One foo() { return this; } <br /> } <br /> class Three extends Two { <br />  // insert method here <br /> } <br /> Which two methods, inserted individually, correctly complete the Three class?()<p> class One { <br />  public One foo() { return this; } <br /> } <br /> class Two extends One { <br /> public One foo() { return this; } <br /> } <br /> class Three extends Two { <br />  // insert method here <br /> } <br /> Which two methods, inserted individually,&ensp
A、A. public void foo() { }
B、B. public int foo() { return 3; }
C、C. public Two foo() { return this; }
D、D. public One foo() { return this; }
E、E. public Object foo() { return this; }