有以下程序：
#include ＜stdio.h＞
main()
char a[30],b[30];
scanf("%s"，a);
gets(b);
printf("%s\n%s\n",a,b);

程序运行时若输入：
how are you I am fine＜回车＞
则输出结果是( )。

A．how are you

I am fine
B．how
are you I am fine
C．how are you

I am fine
D．how are you

两个纳税人能否合并纳税？