Explain – explain functionalities of a product to a user/investor etc.
Feedback – collect feedback on usability and functionality for improvement and further testing
Negotiate – showcase the prototype to investors/stakeholders to get their buy-in
Persuade – prove the product/service potential
In our case, most probably Feedback is what you are looking for. Think of the ways how you will collect and record this feedback and what type of message you are looking for (e.g. whether a customer will buy/use the product, whether the product fulfills its intended use, etc.)