C# XML find first Element descendants
<p>Looking to find <code>categoryId</code> and <code>categoryName</code> for first <code>item</code>.
It could also return no products.</p>

<p>XML Looks like this </p>

<pre><code>&lt;findItemsByKeywordsResponse xmlns="http://..."&gt;
   &lt;ack&gt;Success&lt;/ack&gt;
   &lt;version&gt;1.13.0&lt;/version&gt;
   &lt;timestamp&gt;2016-11-10T17:48:21.321Z&lt;/timestamp&gt;
   &lt;searchResult count="1"&gt;
      &lt;item&gt;
        &lt;itemId&gt;12354&lt;/itemId&gt;
        &lt;title&gt;ABCD#&lt;/title&gt;
        &lt;globalId&gt;ddd&lt;/globalId&gt;
        &lt;primaryCategory&gt;
          &lt;categoryId&gt;**1234**&lt;/categoryId&gt;
          &lt;categoryName&gt;**Catg Nameee**&lt;/categoryName&gt;
        &lt;/primaryCategory&gt;
      &lt;/item&gt;
   &lt;/searchResult&gt;
   &lt;paginationOutput&gt;
   &lt;/paginationOutput&gt;
&lt;/findItemsByKeywordsResponse&gt;   
</code></pre>

<p><em>Full xml <a href="http://svcs.ebay.com/services/search/FindingService/v1?OPERATION-NAME=findItemsByKeywords&amp;SERVICE-VERSION=1.0.0&amp;SECURITY-APPNAME=TriState-d004-4e6c-adee-0fb69d721781&amp;RESPONSE-DATA-FORMAT=XML&amp;REST-PAYLOAD&amp;keywords=065030860819&amp;paginationInput.entriesPerPage=1" rel="nofollow noreferrer">here</a></em></p>