题目内容：
Classmate A : Damn it. My mailbox got packed with loads of Junks.Classmate B:You can use Active Email Monitor, a spam filter, to create any number of filters and so cut down on the amount of junk emails you receive.
Classmate A: Thank you. You really help me a lot.
Classmate B : __________. A．It's my pleasure
B．It's my duty
C．It's my job
D．It's my fault
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