Discuss what is meant by System Development Life Cycle (SDLC) and prototyping [30%]. For what types of system development projects might prototyping be especially useful [10%]? What are the advantages of prototyping and of SDLC [30%]? And what are the risks of each [30%]?

Please use UK English and Oxford format or any UK formats to write the essay.
Can you also provide some additional informations about other IT acquisition options such as buy or lease and outsourcing. However, the main content should still focus on SDLC and prototyping. Though, I prepare this essay for exam use, so I want to have a more general idea about the available options for acquiring Information System applications.