In the context of the Virginia Plan and the New Jersey Plan, the question mark in the diagram should be replaced with "Great Compromise." This is because the Great Compromise (also known as the Connecticut Compromise) was the solution that combined elements from both the Virginia Plan (which favored larger states by proposing representation based on population) and the New Jersey Plan (which favored smaller states by proposing equal representation for each state).
So, the correct answer is: Great Compromise