若定义域为[2a-1，a²+1]的函数f（x）=ax²+bx+2a-b是偶函数，则点（a，b）的轨迹是（　　）

A．一个点

B．两个点

C．线段

D．直线

As part of risk management process，you just created an overall risk ranking of the project，created list of prioritized risks，identified which risks need additional analysis and determined trends in risk analysis results．What should you do next

A．Analyze the effect of risk events and assign a numerical rating to those risk

B．Create a list of identified risk

C．Determine the fundamental conditions or events that may give rise to identified risk(root causes of ri

D．Note down the list of potential responses to the risk