I disagree.
Part III is to guarantee that you're the one who did Part II to some reasonable ability of theirs to verify the matter. Bear in mind that the entire system is really based on the honor system, which means it would be easy enough for you to borrow someone's Part II (or pay someone to do it) and submit it as your own work. Part III, therefore, allows them a safeguard to check ID again and make sure that you know what you're talking about with regards to the assignment you submitted.
While I do agree that it does seem a tad like an extra cash payout for them, it does give them some minor means of trying to assure that you are the one who did Part II, no more and no less.
