title: SelectList with a null selection
body: <p>I have a bunch of drop down lists in my view, such as this one:</p>
  
  <pre><code>@Html.DropDownListFor(model =&gt; model.Process, Model.ProcessList)
  </code></pre>
  
  <p>They all take in a <code>SelectList</code> based on data from a database table like this:</p>
  
  <pre><code>ProcessList = new SelectList(_db.Processes, "ID", "Name");
  </code></pre>
  
  <p>where <code>_db.Processes</code> returns a <code>ObjectSet&lt;Process&gt;</code>.</p>
  
  <p>The issue I have is that sometimes the property that is set by the drop down list can be no selection, i.e. <code>null</code>.  How can I add a <code>null</code> selection to the <code>SelectList</code>></p>