Which two code segments can you use to achieve this goal?

Your Web site processes book orders. One of the application methods contains the following code segment.

XmlDocument doc=newXmlDocument();
doc.LoadXml("<book><discount>10</discount>" +"
<title>Dictionary</title></book>");

You need to remove the discount element from XmlDocument. Which two code segments can you use to achieve this goal?
(Each correct answer presents a complete solution. Choose two.)

A.
XmlNode root=doc.DocumentElement;root.RemoveChild(root.FirstChild);

B.
XmlNode root
=doc.DocumentElement;root.RemoveChild(root.SelectSingleNode("discount"));

C.
doc.RemoveChild(doc.FirstChild);

D.
doc.DocumentElement.RemoveChild(doc.FirstChild);