Which of the following .NET components can be used to remove unused references from the managed heap?

struct Emp
{
    private String name; 
    private int age; 
    private Single sal;
}

1. Emp e(); e = new Emp();
2. Emp e = new Emp;
3. Emp e; e = new Emp;
4. Emp e = new Emp();
5. Emp e;

Sample m = new Sample(); 
int l;
l = m.Length;

Sample m = new Sample(); 
m.Length = m.Length + 20;

Sample.Length = 20;

Console.WriteLine (Sample.Length);

Sample m = new Sample(); 
m.Length = 10;

1. int[] a = {25, 30, 40, 5};

2. int[] a;
   a = new int[3];
   a[0] = 25;
   a[1] = 30;
   a[2] = 40;
   a[3] = 5;

3. int[] a;
   a = new int{25, 30, 40, 5};

4. int[] a;
   a = new int[4]{25, 30, 40, 5};

5. int[] a;
   a = new int[4];
   a[0] = 25;
   a[1] = 30;
   a[2] = 40;
   a[3] = 5;

String s1 = "ALL MEN ARE CREATED EQUAL";
String s2;
s2 = s1.Substring(12, 3); 
Console.WriteLine(s2);

namespace CuriousTabConsoleApplication
{
    class SampleProgram
    {
        static void Main(string[ ] args)
        {
            int i = 10;
            double d = 34.340;
            fun(i);
            fun(d);
        }
        static void fun(double d)
        {
            Console.WriteLine(d + " ");
        }
    }
}