This question is layered. Not only is the interviewer trying to get an idea of who you are, but also an idea of your communication skills, as well as your focus on a team mentality. They're keeping a keen eye out for any 'red flags.' In simplest terms, in this scenario, the last thing you want is to plant the seed that the challenging co-worker in this scenario was you.

Display yourself as a team player, openly and equally accepting everyone on your team. You don't want to come across as part of the reason you and this coworker didn't get along. Avoid assigning blame. Objectify the situation, exhibiting an emotionally mature perspective, and how you navigated this terrain, ultimately leading to a successful resolution. Focus on the positives, and how the overall outcome benefitted the team.

They want to know if you embrace Accenture's attitude towards inclusion and diversity through exemplifying individual respect on all levels. They are also trying to determine whether you're a team-oriented person, and from your perception, what constitutes a "challenging co-worker." On their website, they claim that they expect their interns to have a "can-do" mentality. Having a team mentality means being a people person. Most people fall somewhere in the middle of the scale between an introvert and an extrovert. So this question is also meant to assist in evaluating where you fall on the scale. Only in the rarest of cases do some fall at one end of this extreme.