To answer this question, the user needs to know about the OSI model and the different layers.

The OSI model is a conceptual model that describes how data is transmitted over a network. It has seven layers, each of which has a specific role in the communication process. These layers are:

1. Physical
2. Data Link
3. Network
4. Transport
5. Session
6. Presentation
7. Application

The IP (Internet Protocol) is implemented at the network layer of the OSI model.

Therefore, the correct answer is:

The Answer is: B. network