In which layer of the OSI model does the ICA protocol from Citrix operate?

In which layer of the OSI model does the ICA protocol from Citrix operate?

• Transport
• Application
• Presentation
• Physical               

EXPLANATION

 The Independent Computing Architecture (ICA) protocol operates at the presentation layer of the OSI model, that is, the 6th layer. ICA is a Windows presentation services protocol from Citrix that provides the foundation for turning any client device-thin or fat-into the ultimate thin client. In the case of the ICA protocol, the 6th layer or the presentation layer is responsible for making sure the data can be presented to the application layer, in other words, the presentation layer prepares/formats the data making it ready to be passed up to the application layer.

SOURCE

http://s3.amazonaws.com/legacy.icmp/additional/ica_acceleration_0709a.pdf