Senior Field Coordinator Question:

To err is human. So, it is perfectly OK if you committed a mistake at work but before answering the question analyse the magnitude of mistake you did and the effect it had on the company.

What is more important is - what did you do to rectify the mistake and make sure that you don't do it again?

So, mention the mistake you committed and keep the focus of the answer on the steps you took to rectify it.