If the student performs exactly one experiment, which one of the following could be the colors of the chemicals in th...

Hello I'm confused about question 1 In my setup, I thought that the only way to end up with 2 greens after one experiment is to mix 1 and 4 (since mixing 2 and 4 would use up 2) So the result would be 1: empty 2: Green 3: Blue 4: Green How could there be two greens and a leftover red? The red is required to make the green, and there is no other way to make green I'm assuming there is some key element of this game that I am not understanding, so help would be greatly appreciated, thanks!