The progression in difficulty is great, really hooks you then ramps up
Same for eggplants/aubergines: https://en.wikipedia.org/wiki/Eggplant
For what it's worth, I consider tomato a vegetable too, and so, I failed the level initially. Which, to be honest, mirrors my experience with real captchas - I usually have a disagreement with them, regarding what counts as part of the traffic light etc.