下列程序输出的结果是( )。
#include ＜stdio.h＞
sub1(char a,char b)char c;c=a;a=b;b=c;
sub2(char*a,char b)char c;c=*a;*a=b;b=c;
sub3(char*a,char*b) char c;c=*a;*a=*b;*=c;
void main()

char a,b;
a='A';b='B'; sub1(a,b);putchar(a);putchar(b);
a='A';b='B'; sub2(&a,b);putchar(a);putchar(b);
a='A';b='B'; sub3(&a,&b);putchar(a);putchar(b);
putchar('/n');

A．BABBAB
B．ABBBBA
C．ABBABA
D．ABABBA