Consider the following statements about portlets:

I. Portlets can't contain anything from static HTML content to Java controls to complex web services and process-heavy applications.

II. Portlets are modular panes within a web browser that surface applications, information, and business processes.

III. Portlets can communicate with each other and take part in Java page flows that use events to determine a user’s path through an application.

IV. A single portlet can't have multiple instances − in other words, it can't appear on a variety of different pages within a single portal.

The correct statements are only