以下方法定义中哪个方法是有返回值的？ A.

public int CalculateSum(int x,int y)
{  return x+y;  } B.

public void CalculateSum(int x,int y)
{   Console.Write(x+y);  }
C.

public CalculateSum(int x,int y)
{  
 this.Num1=x;
 this.Num2=y;
}
D.

~public CalculateSum()
{   }