Case 2-1 Casey Is Using XML to Store Information About the Students

Case 2-1
Casey is using XML to store information about the students in the science classes that he teaches. He wants to design a DTD that he can use to validate the XML documents that he uses for this purpose, and he comes to you for help.
-After you teach Casey about declarations for elements with child elements, he constructs the element declaration <!ELEMENT class ((seminar | lesson | workshop) , time?) > . Given this declaration, which of the following is NOT a valid "class" element?

A) <class><seminar>Beginner Drawing</seminar><time>Mon. 3-4</time></class>
B) <class><lesson>One-on-One Painting</lesson><time>Tues. 11-noon</time></class>
C) <class><seminar>Oil Painting</seminar><lesson>brushstrokes</lesson></class>
D) <class><workshop>Working with Clay</workshop></class>