Extreme Programming（XP）is a discipline of software development with（请作答此空）of simplicity,communication,feedback and courage.Successful software development is a team effort-not just the development team,but the larger team consisting of customer,management and developers.XP is a simple process that brings these people together and helps them to succeed together.XP is aimed primarily at object-oriented projects using teams of a dozen or fewer programmers in one location.The principles of XP apply to any（ ）project that needs to deliver quality software rapidly and flexibly.2011-An XP project needs a（ ）customer to provide guidance.Customers,programmers,managers,are all working（ ）to build the system that's needed．Customers-those who have software that needs to be developed-will learn simple,effective ways to（ ）what they need,to be sure that they are getting what they need,and to steer the project to success.
A.importance]
B.keys
C.roles
D.values