PT43.S4.Q18 (G4) - Each of exactly six lunch trucks

BlueRiceCake

I'm confused why the answer isn't x,y,z. Ik the Falafel truck serves 2 at a time but shouldn't it be able to serve all 3 if we cover all possible scenerios?

Admin Note: Edited title. Please use the format: "PT#.S#.Q# - brief description of the question"
https://7sage.com/lsat_explanations/lsat-43-section-4-game-4/