In the following Java code, which call to sum() method is appropriate?

class Output 
{
 
        public static int sum(int ...x)
        {
             return; 
        }
        static void main(String args[]) 
        {    
             sum(10);
             sum(10,20);
             sum(10,20,30);
             sum(10,20,30,40);
        } 
}