问题：

[单选]

You are creating a Windows application by using the .NET Framework 3.5.You create an instance of the BackgroundWorker component named backgroundWorker1 to asynchronously process timeconsuming reports in the application.You write the following code segment in the application （Line numbers are included for reference only.）

You need to write a code segment that reports to the application when the background process detects any of the following actions：  
（1）An exception is thrown  
（2）The process is cancelled  
（3）The process is successfully completed   
Which code segment should you insert？（）

A . A
B . B
C . C
D . D