In the Model-View-Controller (MVC) architecture applied to a Lightning Web Component (LWC) that imports an Apex method:
Controller refers to the logic that handles input and interactions.
In this scenario, when a button is pressed, the method runs to execute complex validations.
Option C: Apex class
Part of Controller.
The Apex class contains the method that performs the complex validations.
It acts as the server-side controller logic.
The JavaScript file of the LWC handles the client-side logic.
It invokes the Apex method when the button is pressed.
The HTML file defines the component's template (View), not the Controller.
Option B: XML file
Configuration File.
The XML file (configuration file) defines metadata about the component, such as where it's available, but it's not part of the Controller.
Conclusion:
The Controller parts in this scenario are the Apex class and the JavaScript file, which are Options C and D.
Reference:
Calling Apex Methods
Option D: JavaScript file
Part of Controller.
JavaScript Controller in LWC
Incorrect Options:
Option A: HTML file
View Layer.