Which of the following statements are correct about an ArrayList collection that implements the IEnumerable interface?

1. The ArrayList class contains an inner class that implements the IEnumerator interface.
2. An ArrayList Collection cannot be accessed simultaneously by different threads.
3. The inner class of ArrayList can access ArrayList class's members.
4. To access members of ArrayList from the inner class, it is necessary to pass ArrayList class's reference to it.
5. Enumerator's of ArrayList Collection can manipulate the array.

1. A class
2. A property
3. A struct
4. A function
5. An interface

class Sample
{
    int i;
    Single j;
    double k;
    public Sample (int ii, Single jj, double kk)
    {
        i = ii;
        j = jj;
        k = kk;
    } 
}

namespace CuriousTabConsoleApplication
{ 
    class SampleProgram
    {
        static void Main(string[] args)
        { 
            int num = 1;
            funcv(num); 
            Console.Write(num + ", "); 
            funcr(ref num); 
            Console.Write(num + ", ");
        }
        static void funcv(int num)
        { 
            num = num + 10; Console.Write(num + ", ");
        }
        static void funcr (ref int num)
        { 
            num = num + 10; Console.Write(num + ", ");
        } 
    } 
}

1. true
2. false
3. new
4. ~
5. sizeof