Which best describes the goal of any proposal? to summarize all available research for the audience to introduce the audience to the solution to persuade the audience to support the plan to explain the problem to the audience

The general goal of a proposal are the following:
1. informative
2. Persuasive
3. Entertain

The answer to the question is "To persuade the audience". This is the primary goal when creating a proposal and presenting your proposal to you clients.