Answer: Executive summary
Explanation:
Executive summary is type of brief document in which description about the business report or business plan is summarized so that the main idea and thought can be understood by the reader. It gives the major idea about the long-body report of business though highlights, summary, etc .
According to the situation Melanie should give executive summary to the invested so that he can understand her business idea without reading the complete business plan.
Other option are incorrect because description about company, strategies for operation, marketing plan and background synopsis is not used for creating brief of business idea.