A. Embedded style sheets enable to embed an entire CSS document in an XHTML document's head section
B. Class Selectors are used in Embedded Style sheets
C. The style element's type attribute specifies the Multipurpose Internet Mail Extensions (MIME) type that describes a file's content
D. All the statements are correct

Solution

C. The style element's type attribute specifies the Multipurpose Internet Mail Extensions (MIME) type that describes a file's content