If this is the case and you have been with only one company your entire career, then the best way to answer this question is to say how many changes you experienced in your previous position. Then it will sound like you are good with change and can adapt to new situations easily.
Saying this confidently is the key. It's not an important question, but more like a question verifying that you are willing and capable of new things. But the more you convince them of your abilities to change, then the better you will appear.