The Systems Development Life Cycle (SDLC) is a process of creating or altering information systems, and the models and methodologies that people use to develop these systems. Sequential SDLC models, such as （）, focus on complete and correct planning to guide large projects and risks to successful and predictable results.

A.Waterfall

B.ExtremeProgramming

C.Spiral

D.RapidPrototyping

蛇曲是河流的沉积作用形成的。（）