The interviewer wants to know what you do when you face a difficult decision. As with the question about stress, be prepared to share an example of what you did in a tough situation.
It’s important to share details around this example in order to make the story believable and engaging. That being said, avoid talking negatively, or extensively, about other people. This can detract from what the interviewer really wants to know about, which is how you perform in a challenging situation.