Câu 20: CPP: C++ Certified Professional Programmer

What happens when you attempt to compile and run the following code?#include #include #include using namespace std;template struct Out {ostream & out;Out(ostream & o): out(o){}void operator() (const T & val ) { out v1(10);sort(t1, t1+5);sort(t2, t2+5);set_union(t1,t1+5,t2,t2+5,v1.begin());for_each(v1.begin(), v1.end(), Out (cout));cout<<endl; return 0;}Program outputs:

1. A. 3 2 4 1 5 6 8 2 1 0
2. B. 1 2 3 4 5 6 8 2 1 0
3. C. 1 1 2 2 3 4 5 5 6 8
4. D. 1 2 3 4 5 6 8 0 0 0 — đáp án hiện tại
5. E. compilation error