Which type of testing in the systems development life cycle (SDLC) focuses on how different...

Integration testing focuses on ensuring that different modules or components of the system work together correctly. This validates that individual units, once combined, interact seamlessly and produce the expected results.

Option B (Parallel testing): Compares old and new systems running together.

Option C (Unit testing): Tests individual components in isolation.

Option D (Acceptance testing): Validates the entire system with user requirements.

Thus, the type of testing that ensures components work together is Integration testing.