When a Lightning component needs to execute a complex SOQL query that joins two objects, and such queries are not supported directly in Lightning components, the solution is to use an Apex controller method.
Option C: Invoke an Apex class with the method annotated as @AuraEnabled to perform the query.
Correct Approach.
The Lightning component can call an Apex method annotated with @AuraEnabled.
The Apex method can perform the complex SOQL query and return the results to the component.
While it's possible to invoke flows from Lightning components, flows are not ideal for executing complex SOQL queries.
Flows have limitations on data manipulation and querying.
Option B: Write the query in a custom Lightning web component wrapper and invoke from the Lightning component.
Not Applicable.
Lightning components (Aura or LWC) cannot execute complex SOQL queries directly.
They must call server-side Apex methods for such operations.
Option D: Use the Salesforce Streaming API to perform the SOQL query.
Incorrect.
The Streaming API is used for subscribing to data changes in real-time.
It is not used for executing queries.
Conclusion:
The Lightning component should invoke an Apex method annotated with @AuraEnabled to perform the complex SOQL query, which is Option C.
Reference:
Lightning Components and Apex
Using Apex to Get Data
Incorrect Options:
Option A: Create a flow to execute the query and invoke from the Lightning component.
Not Optimal.