title: Fastest way to find common items across multiple lists in C#
body: <p>Given the following:</p>
  
  <pre><code>List&lt;List&lt;Option&gt;&gt; optionLists;
  </code></pre>
  
  <p>what would be a quick way to determine the subset of Option objects that appear in all N lists? Equality is determined through some string property such as option1.Value == option2.Value.</p>
  
  <p>So we should end up with <code>List&lt;Option&gt;</code> where each item appears only once.</p>