Dropdown Selenium C #

I'm trying to select a dropdown with selenium C #, but as we can see in the HTML below there is no "ID" or "Name", below the code how am I doing, could you help me?

<select ng-model="vm.activeWhatsapp.channel_id" 
                    ng-options="channel.id as channel.display_name group by channel.sector.name for channel in vm.whatsappChannels" 
                    class="ng-pristine ng-valid ng-empty ng-touched">
                    <option value="?" selected="selected">
                    </option>
                    <optgroup label="Itaú Cartões Ativo">
                    <option label="Liderança - Itaú Cartões Ativo" value="number:1325">Liderança - Itaú Cartões Ativo</option>
                    </optgroup>
                    </select>




    //Selecting a drop down control
    public static  void SelectDropDown(IWebDriver driver, string element, string value, string elementtype)
    {

        if (elementtype == "Id")
            new SelectElement(driver.FindElement(By.Id(element))).SelectByText(value);
        if (elementtype == "Name")
            new SelectElement(driver.FindElement(By.Name(element))).SelectByText(value);
        if (elementtype == "Class")
            new SelectElement(driver.FindElement(By.CssSelector(element))).SelectByValue(value);

SeleniumSetMethods.SelectDropDown(drive, ".ng-pristine.ng-valid.ng-empty.ng-touched", "1325", "Class");