Which line contains a constructor in this class definition？（）   public class Counter { // （1）   int current， step；   public Counter（int startValue， int stepValue） { // （2）   set（startValue）；   setStepValue（stepValue）；  }   public int get（） { return current； } // （3）   public void set（int value） { current = value； } // （4）   public void setStepValue（int stepValue） { step = stepValue； } // （5）  }  

• A、Code marked with （1） is a constructor
• B、Code marked with （2） is a constructor
• C、Code marked with （3） is a constructor
• D、Code marked with （4） is a constructor
• E、Code marked with （5） is a Constructor