Used for requester Lili Dworkin's HIT titled 'Choose Subject of Homework Question'. Use Numpad1-7 keys to select an option. Use the Enter key to submit, or there is also an auto-submit var in the script that you can toggle on or off.
This script also serves as a good boilerplate for hotkey selection HITs that load content considered "outside" of the mturk domain. If you tried to make a script and got a DOMException related to the same-origin policy, this can help you out. Just add the domain the HIT is loading content from to the @match parameter and change the verify HIT to accept yours.