public class Mycircle {  public double radius；  public double diameter；  public void setRadius（double radius）  this.radius = radius；  this.diameter= radius * 2；  }  public double getRadius（）   {  return radius；  }  Which statement is true？（）  

A.  The Mycircle class is fully encapsulated.

B.  The diameter of a given MyCircle is guaranteed to be twice its radius.

C.  Lines 6 and 7 should be in a synchronized block to ensure encapsulation.

D.  The radius of a MyCircle object can be set without affecting its diameter.