单选题

下列程序的运行结果是（） #includeusing namespace ...

Question

下列程序的运行结果是（）

#includeusing namespace stdclass base {public:int nbase(int x) { n = x}virtual void set(int m) { n = m cout << n <<' '}}class deriveA:public base{public:deriveA(int x):base(x) { }void set(int m) { n += m cout << n <<' '}}class deriveB:public base{public:deriveB(int x):base(x) { }void set(int m) { n +=m cout <<n << ' '}}void f(base p){p.set(0)}int main()
{
     deriveA d1(1)
     deriveB d2(3)
     f(d1)
  f(d2)
     return 0
}

A. 0  0

B. 1  3

C. 0  1

D. 0  3