Answer: c) XML tags represent the kind of content being posted and transmitted.
Explanation: XML(Extensible markup language) is the computer markup language that helps in the storing the information, generating flexible data formats and transporting it.
XML tags are the elements that can be created by user for displaying the content of the element and transported.Other options are incorrect because tags are not used for layout description, highly flexible and cannot define content without context. Thus, the correct option is option(C).