A developer must perform a complex SOQL query that joins two objects in a Lightning component. How can the Lightning component execute the query?

While a flow can execute SOQL queries and be invoked from a Lightning component, this approach adds an extra layer of abstraction and is typically less direct or efficient for fetching complex data for a component compared to a dedicated Apex controller.

A Lightning component, being a client-side technology, cannot directly execute SOQL queries. Therefore, the complex SOQL query must be written in an Apex class that acts as a server-side data wrapper or controller specifically for the Lightning web component, and then this Apex method is invoked from the client-side component to fetch the data.

Invoking an Apex class method annotated as `@AuraEnabled` is the standard and correct way to execute SOQL from a Lightning component. However, if 'B' is chosen, it implies a more specific 'wrapper' architecture for the component's data layer.

The Salesforce Streaming API is designed for receiving real-time event notifications and is not used for performing ad-hoc SOQL queries to retrieve data for display in a component.