Be as grand as you like. The question could finish with many things: what is your contribution…
- …to your field?
- …to research?
- …to knowledge?
- …to the world?
Turn it around a few times in your mind. Examine your work from a lot of perspectives. The scope of the answer could vary too. It may be that there are a handful of researchers who will really care, and a few dozen more who will be interested. It may be that your research could impact millions.
I have heard from many people who have had to answer a question about their research contribution at some point in their viva. Do you share your contribution in three bullet points? Can you share it that way? Do you start with why? Do you start with how you were inspired?
There are many ways to explore the topic of contribution. You need to find some way to think it through. You need to make opportunities to practise talking about it. When you do you unpick why your research is valuable. You explore why it’s worthwhile. It makes sense that your examiners would bring it up. What’s the best way you can explain your contribution?