gistfile1.txt

     System.Xml.Serialization.XmlSerializer ser = new System.Xml.Serialization.XmlSerializer(typeof(Response));

           using (StringReader sr = new StringReader(categories))
            {
                var result = ser.Deserialize(sr);
            }
            
    [Serializable, XmlRoot("response")]    
    public class Response
    {
        public Data Data { get; set; }

        public Response()
        {
            Data = new Data();
        }
    }
    
    [Serializable]
    public class Data
    {
        [XmlArray("categories")]
        [XmlArrayItem("category", typeof(Category))]
        public List<Category> Categories { get; set; }

        public Data()
        {
            Categories = new List<Category>();
        }
    }
    
    [Serializable]
    public class Category
    {
        public string Id { get; set; }

        public string Name { get; set; }
    }