单选题：以下程序的输出结果是publicclassko_{publicstaticvoidmain(Stringargs[]){intsum=;intko[][]={{，，}，{，，}，{，，}};for(intn=;nfor(intm=;msum+=ko[n][m];System.out.println(“sum=”+sum);}}Asum=Bsum=Csum=Dsum=