title: Comapring two List<String> to extract the common items and put it in List
body: <p>Im having two List items, how can I write a linq query to compare both and extract the common items.(Like List c, as shown below)</p>
  
  <pre><code>List&lt;string&gt; a = {a, b, c, d}
  List&lt;string&gt; b = {c, d, e, f}
  
  List&lt;string&gt; c = {c, d}
  </code></pre>