Which method is used to send data from a child component to a parent component in LWC?

In Lightning Web Components (LWC), the method used to send data from a child component to a parent component is the dispatchEvent method. This method is part of the event handling mechanism in LWC, where the child component can create a custom event that carries data. The custom event is then dispatched, allowing the parent component to listen for this event and respond accordingly.

When a child component uses dispatchEvent, it effectively communicates information back to the parent component. This is done by creating an instance of the CustomEvent class, which can include additional data in its detail property. The parent component can listen for the custom event using the on<EventName> syntax in its template and process the data when the event is fired.

This pattern of using events is fundamental for maintaining a clear communication pathway in a component hierarchy, ensuring that child components remain reusable and independently functioning while still being able to communicate with their parent components.

The other choices do not align with the standard way of communicating from child to parent in LWC; they are either methods that do not exist in LWC or concepts that do not correctly represent event handling practices in this framework.