that's #16, though perhaps I should just say that the reason the response is empty is that Google is redirecting you. I'd love more suggestions for curl exercises though :)
<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>301 Moved</TITLE></HEAD><BODY>
<H1>301 Moved</H1>
The document has moved
<A HREF="https://www.google.com/">here</A>.
</BODY></HTML>
So not an empty response...Another exercise could be to have a page where the Access Control Allow Origin is set to a specific domain, then make a request by setting a different origin.
E.g:
curl -H "Origin: https://wrong.origin.com" https://httpbin.org/anything
Many people think CORS is enforced by the server.