As a co-founder of your company, one of your most important roles is salesperson, regardless of your title within the company.  In order to make a customer sale, raise capital, recruit a key team member, etc., you will have to convince your target that your venture is worth their while. 
Your final individual assignment is to persuade someone to support your effort. You pick the target: recruit, investor, customer, etc. (make sure your intended audience is clearly identified or is obvious by the nature of your response).  Make an argument to convince your target.  Be sure to support your case with things you’ve learned from working on your team project, for example, solving customer pain, equity to early hires, or return for investors.  The format or medium is up to you.  A few examples include a recorded sales pitch or commercial that you upload to YouTube, an investor pitch deck, a sample Kickstarter video, a job offer letter for a new recruit, a Prezi, a cartoon, or a 1-2 page typed paper…  Here’s an example of a creative submission from a previous semester: https://youtu.be/eNrq9-sk6Nk
Use your imagination and make it compelling.  Be creative and captivate your audience.  Holding their attention is half the battle.  It doesn’t need to be long or elaborate, just convincing.  Do what you think best supports your case, and choose a medium in which you’re confident.  Take some risks.  You have license to be creative and have fun with this!