Which of the following statements is correct about the C#.NET program given below?

namespace CuriousTabConsoleApplication
{
    class Baseclass
    { 
        int i;
        public Baseclass(int ii)
        {
            i = ii;
            Console.Write("Base "); 
        } 
    } 
    class Derived : Baseclass
    {
        public Derived(int ii) : base(ii)
        {
            Console.Write("Derived ");
        } 
    } 
    class MyProgram
    { 
        static void Main(string[ ] args)
        { 
            Derived d = new Derived(10);
        } 
    } 
}

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