What will be the output of the following C code?

#include <stdio.h>
int main()
{
    void foo(), f();
    f();
}
void foo()
{
    printf("2 ");
}
void f()
{
    printf("1 ");
    foo();
}

A. Decision making B. Variable declaration C. Code organization and reusability D. Printing output

A. To declare a function's return type B. To declare a function's name C. To declare a function's parameters and return type D. To declare a function's name and parameters

A. 4 B. 8 C. 2 D. Error

A. By value B. By reference C. By pointer D. By address