An email contains a texual birthday greeting, a picture of a cake and a song. The order is not important. What is the content-type?
B is the ans.
The primary subtype for multipart, "mixed", is intended for use when the body parts are independent and intended to be displayed serially. Any multipart subtypes that an implementation does not recognize should be treated as being of subtype "mixed"
This document defines a "parallel" subtype of the multipart Content-Type. This type is syntactically identical to multipart/mixed, but the semantics are different. In particular, in a parallel entity, all of the parts are intended to be presented in parallel, i.e., simultaneously, on hardware and software that are capable of doing so. Composing agents should be aware that many mail readers will lack this capability and will show the parts serially in any event
http://highered.mheducation.com/sites/0072515848/student_view0/chapter26/mixed_quiz.html
Answer : it should be Multi-part/mixed (As they said order is not important that is how it is mixed)
A content type is a reusable collection of metadata (columns), workflow, behavior, and other settings for a category of items .Content types enable you to manage the settings for a category of information in a centralized, reusable way.
B) Multipart/parallel