This is one of the most frequently asked questions. The response to this question is quite generic, but it works all the time. When I interviewed with MBB, this is how I answered the question and you can follow a similar logic:
I focused on the fact that I was a recent graduate who did not know what to specialize in, in terms of industries (e.g. healthcare, consumer goods, retail, etc.) or functional topics (e.g., finance, HR, strategy, digital, etc.). Thus I emphasized that I wanted to get into consulting to better understand what I am passionate about by working on a different set of projects.
Moreover, I also mentioned that the skillset that I will acquire in consulting (e.g., team management, time management, client management) would be applicable anywhere I go next.
Lastly, I also highlighted the opportunity to take up significant responsibilities in the early stages of my career, as it is rare to find someone who is in his/her mid-20s sit on the same table with key industry leaders and make recommendations to them.