Rule 1
10 ATCOs - 11 different opinions. This is one of the best illustrations of this phenomenon.
The interviewer is trying to look at your reasoning and decision-making ability. If you can come up with an answer and justify it, change it if alternative circumstances warrant it, without bull-****ting, you are answering the question correctly.
If you send all the blue ones, then the red ones, or go for the one with the least number of wheels first, or alphabetically, you'll probably be going home.