题目：Which of the following is true?（） 下列哪个语句是正确的？（）
A. One of the reasons of software crisis is the lack of document. So we should take a separate phase of the software life cycle to achieve sufficient document.
B. Since there are kinds of software lifecycle models, we should choose the best one for the target project.
C. Since there are kinds of software lifecycle models, we should choose the most suitable one for target project.
D. The requirement of the software only concerns its functionality.
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