Html Agility Pack cannot find list option using xpath
See the question and my original answer on StackOverflowThis is "by design". It's the same idea for OPTION and FORM. Some tags are handled differently because of historical reasons by the Html Agility Pack. Back then in HTML 3.2 time, OPTION was not always closed, and in HTML 3.2, it's not required.
Try adding this:
HtmlNode.ElementsFlags.Remove("option");