How would you answer an interview scenario involving dependency injection and SOLID?

For an interview scenario involving dependency injection and SOLID, I would first clarify the business goal, scale, constraints, and the failure or quality attribute the interviewer wants to explore. Dependency injection supplies collaborators from outside a component and often supports DIP, testability, and composition. In this scenario, a handler has fifteen constructor dependencies. Explain what you would investigate before simply accepting it. For production, use constructor injection for required dependencies, keep lifetimes correct, and treat large dependency lists as a design signal. I would then explain the main alternatives and tradeoffs, identify likely failure modes, and describe how I would validate the solution through testing, observability, security controls, and recovery or rollback planning.