There's no multiple choice here, just type what you think is the correct answer in the box. You get three guesses before we give up and tell you. Let's go!
1. Let's start easy.
4. Things are about to get a bit harder.
7. Keep going...
So... how did you do?
Kelly Oakes is science editor for BuzzFeed and is based in London.
Contact Kelly Oakes at firstname.lastname@example.org.
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