Which of the following is NOT a namespace in the .NET Framework Class Library?

char ch = Convert.ToChar ('a' | 'b' | 'c'); 
switch (ch)
{
    case 'A': 
    case 'a':
    Console.WriteLine ("case A | case a");
    break;
    
    case 'B': 
    case 'b':
    Console.WriteLine ("case B | case b");
    break;
    
    case 'C':
    case 'c':
    case 'D':
    case 'd':
    Console.WriteLine ("case D | case d");
    break;
}

int i, j, id = 0; switch (id)
{ 
    case i:
        Console.WriteLine("I am in Case i");
        break; 
    
    case j:
        Console.WriteLine("I am in Case j");
        break;
}

1. Type safety of the code running under CLR is assured.
2. It is ensured that an application would not access the memory that it is not authorized to access.
3. It launches separate process for every application running under it.
4. The resources are Garbage collected.

namespace CuriousTabConsoleApplication
{ 
    class Sample
    { 
        public int func()
        {
            return 1;
        } 
        public Single func()
        { 
            return 2.4f ;
        } 
    } 
    class Program
    { 
        static void Main(string[ ] args)
        {
            Sample s1 = new Sample(); 
            int i;
            i = s1.func(); 
            Single j; 
            j = s1.func(); 
        } 
    } 
}

namespace CuriousTabConsoleApplication
{
    class SampleProgram
    {
        static void Main(string[ ] args)
        {
            int i, j;
            int[ , ] arr = new int[ 2, 2 ];
            for(i = 0; i < 2; ++i)
            {
                for(j = 0; j < 2; ++j)
                {
                    arr[i, j] = i * 17 + i * 17;
                    Console.Write(arr[ i, j ] + " ");
                }
            }
        }
    }
}

int i = 0; 
do
{
    Console.WriteLine(i);
    i+ = 1; 
} while (i <= 10);

int i = 0; 
do
{
    Console.WriteLine(i);
} until (i <= 10);

int i;
for (i = 0; i <= 10 ; i++)
    Console.WriteLine(i);

int i = 0; 
while (i <= 11)
{
    Console.WriteLine(i);
    i += 1; 
}

int i = 0;
do while ( i <= 10)
{
    Console.WriteLine(i); 
    i += 1;
}

int i = 0;
do until (i <= 10)
{
    Console.WriteLine(i);
    i+=1; 
}

int i = 1, j = 1, val;
while (i < 25)
{
    Console.Write(j + " ");
    val = i + j;
    j = i;
    i = val;
}

1. A function cannot be called from a subroutine.
2. The ref keyword causes arguments to be passed by reference.
3. While using ref keyword any changes made to the parameter in the method will be reflected in that variable when control passes back to the calling method.
4. A subroutine cannot be called from a function.
5. Functions and subroutines can be called recursively.