The correct answer is A. A popstate event is fired with a state property that details the application's last state.

When window.history.pushState() is used to add entries to the browser's history:

It creates a new history entry without reloading the page
When the user clicks the back button, the browser:
Moves back one step in the history stack
Fires a popstate event
The event object contains a state property with the state data from the previous entry
Example of handling this:

JavaScript

window.addEventListener('popstate', (event) => {
if (event.state) {
// Restore application to the state stored in event.state
updateUI(event.state);
}
});
The other options are incorrect because:

The page doesn't reload (option B)
There's no standard "navigate" event in this context (option C)
The page isn't navigated away from - navigation happens within the single-page context (option D)