You have inputs on HEC website: 10mn of presentation, about the topic of your choice. While a lot of people pick up random subject, I would recommend to present a business related subject or related to YOU, means YOUR application. Make the link, show you enthusiasm about it, and that you believe in your application/project.
If you like to tell stories, 6 slides should be great. If you are passionate about this subject, you will do it well.
As HEC says, be knowledgeable about this subject, enthusiast, train on your pace, and show you have the qualities the school looks for: passion, Innovation and personal skills.
A good strategy is to be able to give a flavor of your application with this presentation, thus enabling you to switch to the interview part naturally.
You have plenty of feedbacks on the web that can guide you. In the end, just be yourself.
Hope it helps.
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