write a short paper describing the history and differences between Six Sigma, Waterfall, Agile, and Scrum models. Understanding these models can give you a good idea of how diverse and interesting IT development projects can be. Describe what the rationale for them is and describe their key features. Describe the history behind their development Search the web for information on these topics and describe where they are most effectively used. The length of the paper should be at least 400 words and should include all three models, their basic definitions, for what kind of projects they are used, and their limitations or drawbacks.