What will the following code display?

```
#include
using namespace std;
void showDub(int);
int main()
{
int x = 2;
showDub(x);
cout << x << endl;
return 0;
}
void showDub(int num)
{
cout << (num * 2) << endl;
}
```

a. 2
2
b. 4
2
c. 2
4
d. 4
4

b. 4
2