[单选]  #include      voidmain(){          inta[3][4]={{1,2,7,8},{5,6,10,6},{9,12,3,4}};          intm=a[0][0];          inti,j;          for(i=0;i<3;i++)              for(j=0;j<4;j++)                  if(a[i][j]>m)m=a[i][j];          printf(“%dn“,m);      }