Professional Experience Question:

You should try to speak positively about your colleagues, while not completely ignoring possible negative aspects.
You can reply to this question with this answer:
I had an excellent professional relationship with my co workers, which gelled quite nicely with the company environment. People assisted one another. We worked as a team to solve problems and learned new skills to reach our team objectives.
I made some good friends for life, who today can vouch for me on a professional basis.