Which of the following statement is correct about a String in C#.NET?

1. Single f = 9.8f; 
   String s;
   s = (String) (f);

2. Single f = 9.8f; 
   String s;
   s = Convert.ToString(f);

3. Single f = 9.8f; 
   String s;
   s = f.ToString();

4. Single f = 9.8f; 
   String s;
   s = Clnt(f);

5. Single f = 9.8f; 
   String s;
   s = CString(f);

1. String is a value type.
2. String literals can contain any character literal including escape sequences.
3. The equality operators are defined to compare the values of string objects as well as references.
4. Attempting to access a character that is outside the bounds of the string results in an IndexOutOfRangeException.
5. The contents of a string object can be changed after the object is created.

String str = "She sells sea shells on the sea-shore"; 
int i;
i = str.SecondIndexOf("s");

String str = "She sells sea shells on the sea-shore"; 
int i, j;
i = str.FirstIndexOf("s"); 
j = str.IndexOf("s", i + 1);

String str = "She sells sea shells on the sea-shore"; 
int i, j;
i = str.IndexOf("s"); 
j = str.IndexOf("s", i + 1);

String str = "She sells sea shells on the sea-shore"; 
int i, j;
i = str.LastIndexOf("s"); 
j = str.IndexOf("s", i - 1);

String str = "She sells sea shells on the sea-shore"; 
int i, j;
i = str.IndexOf("S"); 
j = str.IndexOf("s", i);

namespace CuriousTabConsoleApplication
{
    class SampleProgram
    {
        static void Main(string[ ] args)
        {
            string str= "Hello World!";
            Console.WriteLine( String.Compare(str, "Hello World?" ).GetType() );
        }
    }
}

String s1 = "String";
String s2; 
s2 = s1;

String s1 = "String" ; 
String s2;
s2 = String.Concat(s1, s2);

String s1 = "String"; 
String s2;
s2 = String.Copy(s1);

String s1 = "String"; 
String s2;
s2 = s1.Replace();

String s1 = "String"; 
String s2;
s2 = s2.StringCopy(s1);

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

String s1="Kicit";
Console.Write(s1.IndexOf('c') + " "); 
Console.Write(s1.Length);

enum color : byte
{
    red = 500,
    green = 1000,
    blue = 1500
}

enum per
{
    married, 
    unmarried, 
    divorced, 
    spinster
}
per.married = 10; 
Console.WriteLine(per.unmarried);

enum color
{
    red,
    green,
    blue 
}
color c; 
c = color.red; 
Console.WriteLine(c);