There’s no right or wrong answer here, but you want to be diplomatic. Regardless of whether you’re an extrovert or an introvert, it’s crucial your answer clearly shows that you’re versatile. Share your preference, but also keep the role itself in mind. If you’re an event planner, hopefully you like working with others.
For a great answer, include two positive examples: one in which you worked well with a group and another in which you worked well on a solo project.
I love working on a team. When I interned with XYZ Company, there were issues with a few fellow interns not getting along. I intervened, organized a social gathering for the group, and it really helped them put their differences aside. We finished the summer on a great note and came up with the best ideas by putting our heads together. At the same time, I enjoy working independently when necessary. In school, I prided myself on never missing an essay deadline. That was because I’m able to put my head down and focus.