Modern science and technology has ___ communication between people far apart.

A．made convenient

B．made it convenient

C．made it convenient for

D．made it convenient to

有以下程序：
main()
int a[4][4]=1,4,3,2,,8,6,5,7,,3,7,2,5,,4,8,6,1,),i,j,k,t；
for(i=0;i＜4;i++)
for(j=0;j＜3;j++)
for(k=j+1;k＜4;k++)
if(a[j][i]＞a[k][i])t=a[j][i];a[j][i]=a[k][i];a[k][i]=t;/*按列排序*/
for(i=0;i<4;i++)printf("%d,",a[i][i])；

程序运行后的输出结果是______。

A) 1,6,5,7,
B) 8,7,3,1,
C) 4,7,5,2,
D) 1,6,2,1,