Explanation:

In Aura components, application events follow the publish-subscribe model, meaning any component that registers for the event can handle it when it's fired. To trigger an Aura application event, developers use the fire() method.

How it works:

Define the event using the tag.
Register the event in the component that will handle it.
Fire the event using event.fire() in the component that triggers the event.

Analyzing the incorrect options:

A. ernit() – This method doesn't exist in Aura event handling.
B. fireEvent() – This is an incorrect method; fire() is the correct one.
D. registerEvent() – This method is used to register an event in the component, not to fire it.