Which of the following is the correct code for invoking a function without this

Which of the following is the correct code for invoking a function without this keyword at all, and also too determine whether the strict mode is in effect?

2) Consider the following code snippet

function f() {};

3) Consider the following code snippet

function printprops(o)
  {
     for(var p in o)
       console.log(p + ": " + o[p] + "\n");
 }

4) Consider the following code snippet :

 var c = counter(), d = counter();
  c.count()
 d.count()
  c.reset()
  c.count()
  d.count()

5) What is the difference between the two lines given below ?

  !!(obj1 && obj2); (obj1 && obj2);