Which message pattern should you choose?

You are developing a WCF service that compares several data sources. The service takes a
long time to complete. The service must meet the following requirements:
• The client must be able to continue processing while the service is running.
• The service must initiate communication with the client application when processing
is complete.
You need to choose a message pattern to meet the requirements. Which message pattern
should you choose?

A.
One Way

B.
Streaming

C.
Duplex

D.
Request/Reply