有如下程序:#includeusing namespace std;class Boat;class Car{public:Car(int i):weight(i){ }friend int Total(const Car &c.const Boat &b); ①private:int weight;};class Boat{public:Boat(int i):weight(i){ }friend int Total(const Car &c,const Boat &b);private: int weight;};int Total(const Car &c,const Boat &b){ ②return c.weight+b.weight;}int main(){Car c(10);Boat b(8);cout<< The total weight is <<Total(c,b)<<endl; ③return 0;}下列关于程序的描述中,正确的是
A.程序编译正确
B.程序编译时语句①出错
C.程序编译时语句②出错
D.程序编译时语句③出错