Which of the following statements about a String is correct?

1. String s = "123"; 
   int i;
   i = (int)s;

2. String s = "123";
   int i;
   i = int.Parse(s);

3. String s = "123"; 
   int i;
   i = Int32.Parse(s);

4. String s = "123"; 
   int i;
   i = Convert.ToInt32(s);

5. String s = "123"; 
   int i;
   i = CInt(s);

String s1 = "Nagpur";
String s2;
s2 = s1.Insert(6, "Mumbai"); 
Console.WriteLine(s2);

String s1, s2; 
s1 = "Hi"; 
s2 = "Hi";

1. String objects cannot be created without using new.
2. Only one object will get created.
3. s1 and s2 both will refer to the same object.
4. Two objects will get created, one pointed to by s1 and another pointed to by s2.
5. s1 and s2 are references to the same object.

1. Two strings can be concatenated by using an expression of the form s3 = s1 + s2;
2. String is a primitive in C#.NET.
3. A string built using StringBuilder Class is Mutable.
4. A string built using String Class is Immutable.
5. Two strings can be concatenated by using an expression of the form s3 = s1&s2;

1. if(s1 = s2)

2. if(s1 == s2)

3. int c;
   c = s1.CompareTo(s2);

4. if( strcmp(s1, s2) )

5. if (s1 is s2)

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);

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

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);