单选题：请读程序：

请读程序：
```
#include
#define LETTER 0
int main()
{
char str[20]=“C Language”,c;
int i;
i=0;
while((c=str[i])!=‘\0’)
{
i++;
#if LETTER
if(c>=‘a’&&c<=‘z’)
c=c-32;
#else
if(c>=‘A’&&c<=‘Z’)
c=c+32;
#endif
printf(“%c”,c);
}
return 0;
}
```
上面程序的运行结果是@[B](2)
A. C Language
B. c language
C. C LANGUAGE
D. c lANGUAGE



A.C Language
B.c language
C.C LANGUAGE
D.c lANGUAGE


答案：B