This would be more accurate if you called it guilds of Ravnica, since these guilds do not exist outside the plane of Ravnica- they've only been used in two blocks so far which is a tiny portion of MtG overall. Also... if you type in "gruul" it won't accept this as an answer for Gruul. You have to type in "grul" to get Gruul... might want to fix that.
Maybe you could expand it by adding in the Alara Shards as well... Bant, Jund, Esper and so on. If I were doing the quiz myself I would have made the hints colors, not lands.
You're welcome. :) So what's your guild? I went 4-0 in the MTGO prerelease sealed going with a mostly Azorius deck, splashes of Simic and a tiny bit of Selesnya. Had so many bombs in my packs though I had to leave Hydra in the sideboard.