why object.ReferenceEquals(u, c)=false

Question

class Program
{
static void Main(string[] args)
{
string a = "len";
string b = "len";
string c = new StringBuilder(a).ToString();
Console.WriteLine(c);
Console.WriteLine(object.ReferenceEquals(a,c));
string u = string.Intern(c);
Console.WriteLine(object.ReferenceEquals(u, c));
Console.ReadKey();
}
}

Answer 1

because they are different when you use string.intern

Answer 2

but they have same value and interning says produce new string with this reference why c cant be reference in this satiation