title: How to change reference of Base object to Derived which was instatiated as Derived type
body: <p>Why am i not able to access M3 method from Derived ?
  Intellisense shows only M1 and M2 from Base class.
  How can i change the reference of bc from Base type to Refernce Type, 
  so that i can access M3 method.</p>
  
  <pre><code>class Program
  {
      static void Main(string[] args)
      {
          Base bc = new Derived();
          bc.M3():// error
      }
  }
  
  class Base
  {
      public void M1()
      {
          Console.WriteLine("M1 from BASE.");
      }
      public void M2()
      {
          Console.WriteLine("M2 from BASE.");
      }
  }
  
  class Derived : Base
  {
      public void M3()
      {
          Console.WriteLine("M3 from DERIVED.");
      }
  }
  </code></pre>