单选题 有如下程序：
#include＜iostream＞
using namespace std;
class Book{
public:
Book(char*t=" "){strcpy(title,t);}
______
pnvate:
char title[40];
};
class Novel:public Book{
public:
Novel(char*t=" "):Book(t){}
char*Category()const{retum"文学";}
};
int main(){
Book*pb;
pb=new Novel();
cout＜＜pb-＞Category();
delete pb;
retum 0;
}
若程序运行时输出结果是"文学"，则横线处缺失的语句是______。