Here is an example:
<status>200</status>
<requestId>yyy-zzz-aaa</requestId>
<photos>
<twitter>
<typeName>Twitter</typeName>
<url>http://example.com</url>
</twitter>
</photos>
For example, you can then reference photos.twitter[0].url as the Response Attribute and then map that to any Marketo field. Let me know if that makes sense?