Sharepoint 2013 ADD CHOICE  to sharepoint list Programatically CSOM .

CODE:

baseUrl = "http://sharepointsite:1234/sites/abcd";
                    context = new ClientContext(baseUrl);
                    network = context.Web;
                    List People = network.Lists.GetByTitle("List Name");
                    Field f = People.Fields.AddFieldAsXml("<Field Type='Choice' DisplayName='col name ' Name='col name ' Format='Dropdown' Required='TRUE' Indexed='TRUE'><CHOICES><CHOICE>A</CHOICE><CHOICE>B</CHOICE><CHOICE>C</CHOICE></CHOICES><Default>A</Default><Description>choices </Description></Field>", false, AddFieldOptions.DefaultValue);
                    FieldChoice COLNAME= context.CastTo<FieldChoice>(f);
                   
                    COLNAME.Required = true;
                    COLNAME.Update();
                    context.ExecuteQuery();