By clicking which key the PubNub will display public, subscribe, and secret keys.

The correct answer is C. portal.

A portal is a web-based application that provides a single point of access to a variety of services. In the case of PubNub, the portal is where you can create and manage your PubNub account, as well as view your public, subscribe, and secret keys.

The other options are incorrect because:

• A pane is a window or frame in a graphical user interface.
• A demo keyset is a set of keys that you can use to test PubNub without having to create an account.
• A network is a group of computers that are connected together.

I hope this helps! Let me know if you have any other questions.