Extreme Programming (XP) is a discipline of sofiware development with (1) of simplicity,communication, feedback and cuurage. 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 success 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 (2) project that needs to deliver quality software rapidly and flexibly. An XP project needs a (3) customer to provide guidance. Customers, programmers, managers, are all working (4) to build the system that's needed, Customers - those who have software that needs to be developed - will learn simple, effective way to (5) what they need, to be sure that they are getting what they need, and to steer the project to success.空白（3）处应选择（）

A. part-time
B. casual
C. seldom
D. full-time