Final answer:
DARPA is not involved in the HTML5 cooperation, while W3C and WHATWG are the entities that collaborated on its development.
Step-by-step explanation:
The answer to the student's question about HTML5 cooperation is that DARPA is not part of the cooperation that developed HTML5. The two entities that are part of this cooperation are the World Wide Web Consortium (W3C) and the Web Hypertext Application Technology Working Group (WHATWG). HTML5 is a markup language used for structuring and presenting content on the World Wide Web. It is the fifth and current major version of the HTML standard.