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.