A and B. <CFXML> creates XML Document Objects, as does XMLParse() (by converting an XML document to a Document Object). C and D are valid functions but do not create XML Document Objects.
A2:
D. ToString() creates an XML document from an XML Document Object. XMLParse() is exactly the opposite. XMLFormat() creates XML-safe text, and ToXML() does not exist.
A3:
A and D. XML documents may indeed be case sensitive, and they must be well formed (which is why ToString() should be used to generate the XML document). XML is not in a binary format (it is plain text), and it does not (or should not) contain page-formatting information; XML describes data (not layout, as HTML does).