Discuss perfect competition and long-run equilibrium

Answer the following scenario thoroughly utilizing key terms and concepts covered in the previous units reflecting full understanding of the concept of macro economics as it relates to the scenario described. Provide examples and clear rationalizations for your statements.
Essay should be no less than five pages in length double-spaced. Describe your own interpretations utilizing the information you have learned in this course. Support your statements and rationalizations utilizing credible supporting references.

Discuss perfect competition and long-run equilibrium. Provide detailed descriptions, definitions and concrete examples of your findings. Additionally, how does the proliferation of global trade and competition contribute to markets moving more away from market-possessing power to more perfect competition? Lastly, when does marginal social benefit equal marginal social cost and why?