The developer should publish a message on a message channel to implement the communication between the Lightning web components. A message channel is a Lightning web component feature that allows the developer to communicate across the DOM between any components that are listening on the channel. The developer can use the @wire decorator to subscribe to a message channel, and use the publish() function to publish a message on the channel. The message can contain any data that the components need to share, such as the search results. The components that are subscribed to the channel will receive the message and handle it accordingly. Firing an application event will not work, as application events are a Lightning Aura component feature, not a Lightning web component feature, and they are used to communicate across the entire Lightning Experience application, not across the DOM. Publishing an event on an event channel will not work, as event channels are used to publish and subscribe to platform events, which are events that represent changes in Salesforce data or processes, not custom events that represent changes in component data. Firing a custom component event will not work, as custom component events are used to communicate between a parent and a child component in the same DOM tree, not between unrelated components in different DOM trees. Reference: [Communicate Across the DOM], [Lightning Web Components Developer Guide]