This question can mean that hiring managers are curious about other firms. Common reasons for them doing so include wanting to feel out the competition, seeing how serious you are about the industrial engineering industry, or wanting to gauge their likelihood of hiring a strong candidate.

If you answer that you are not interviewing anywhere else, that gives the interviewer a lot more leverage than they already have. The correct answer is as follows: 'Your organization is not the only firm where I have scheduled interviews. In fact, I am actively exploring options within the industrial engineering field with other companies. That being said, I am most excited about the position within your organization.'