c# - How to get value from a <SELECT> <OPTION> -

i'm trying element <select> , <option> element.

this code:

for(int td = 1; td <= 1; td++) {     using (webclient wc = new webclient())     {         string pagina = wc.downloadstring("http://www.serebii.net/attackdex-xy/");         htmldocument doc = new htmldocument();         doc.loadhtml(pagina);          string attacco;         //var prova = doc.documentnode.selectsinglenode("/html/body/table[2]/tr[2]/td[2]/div[2]/table/tr/td[1]/form/select/option");          foreach (htmlnode node in doc.documentnode.selectnodes(string.format("/html/body/table[2]/tr[2]/td[2]/font/div[2]/table/tr/td[{0}]/select/option", td)))         {             attacco = node.nextsibling.innertext;              if(attacco != "attackdex: - g\n" && attacco != "attackdex: h - r\n" && attacco != "attackdex: s - z\n")             {                 var url = string.format("http://www.serebii.net/attackdex-xy/{0}.shtml", attacco.tolower().replace(" ", ""));                 string attackpage = wc.downloadstring(url);                 htmldocument doc2 = new htmldocument();                 doc2.loadhtml(attackpage);                  var category = doc.documentnode.selectsinglenode("/html/body/table[2]/tr[2]/td[2]");             }         }     } } 

and code of html page:

<select name="selecturl" onchange="document.location.href=document.nav.selecturl.options[document.nav.selecturl.selectedindex].value" style="color:#383838; font-size: 8pt; background:#cebc77" size="1">  <option>attackdex: - g </option><option value="/attackdex-xy/absorb.shtml">absorb</option> <option value="/attackdex-xy/acid.shtml">acid</option> <option value="/attackdex-xy/acidarmor.shtml">acid armor</option> <option value="/attackdex-xy/acidspray.shtml">acid spray</option> <option value="/attackdex-xy/acrobatics.shtml">acrobatics</option> <option value="/attackdex-xy/acupressure.shtml">acupressure</option> <option value="/attackdex-xy/aerialace.shtml">aerial ace</option> <option value="/attackdex-xy/aeroblast.shtml">aeroblast</option> [...] 

when run program value of node (in foreach block) null.

i got work selecting options in document, filtering ones have ancestor select tag name 'selecturl'.

doc.documentnode.selectnodes("//option[ancestor::select[@name='selecturl']]")