合同变更一般包括以下活动：
①变更实施
②变更请求审查
③变更批准
④变更提出
以上活动正确的排列顺序是（）

单项选择题（）is a process of monitoring the status of the project to update the project costs and manage changes ti the cost baseline.

A.plan cost management
B.estimate costs
C.determine budget
D.control costs

单项选择题（）is a process of developing a detailed description of the project and product.

A.collect requirements
B.definition scope
C.validate scope
D.control range