Which of the following statements may completely ignore their bodies (inner statements)? (Choose three.)

What happens when you attempt to compile and run the following code?
#include <iostream>
using namespace std;
int mul (int a, int b=2)
{
int r;
r=a*b;
return (r);
}
int main ()
{
cout << mul(1) << mul(2,4);
return 0;
}

What happens when you attempt to compile and run the following code?
#include <iostream>
using namespace std;
namespace myNamespace1
{
int x = 5;
int y = 10;
}
namespace myNamespace2
{
float x = 3.14;
float y = 1.5;
}
int main () {
namespace newname = myNamespace1;
using namespace newname;
cout << x << " ";
cout << y;
return 0;
}

What happens when you attempt to compile and run the following code?
#include <iostream>
#include <string>
using namespace std;
class A {
public:
int age;
A () { age=5; };
};
class B : private A {
string name;
public:
B () { name="Bob"; };
void Print() {
cout << name << age;
}
};
int main () {
B b,*ob;
ob = &b;
ob?>age = 10;
ob?>Print();
return 0;
}

What will be the output of the program?
#include <iostream>
using namespace std;
int main()
{
const int y = 5;
const x = ?10;
cout<<x<<" "<<y;
return 0;
}