Which of the following testing methods tests the system efficiency by systematically selecting the
suitable and minimum set of tests that are required to effectively cover the affected changes?

A.
Unit testing

B.
Integration testing

C.
Acceptance testing

D.
Regression testing

Explanation:
Regression testing focuses on finding defects after a major code change has
occurred. Specifically, it seeks to uncover software regressions, or old bugs that have come back.
Such regressions occur whenever software functionality that was previously working correctly
stops working as intended. Typically, regressions occur as an unintended consequence of
program changes, when the newly developed part of the software collides with the previously
existing code. Regression testing tests the system efficiency by systematically selecting the
suitable and minimum set of tests that are required to effectively cover the affected changes.
application is tested separately. During unit testing, a developer takes the smallest unit of an
application, isolates it from the rest of the application code, and tests it to determine whether it
works as expected. Unit testing is performed before integrating these independent units into
modules. The most common approach to unit testing requires drivers and stubs to be written.
Drivers and stubs are programs. A driver simulates a calling unit, and a stub simulates a called
implementation into the production environment. It is done either by a client or an application
incorrect. Integration testing is a software testing that seeks to verify the interfaces between
components against a software design. Software components may be integrated in an iterative
way or all together (“big bang”). Normally the former is considered a better practice since it allows
interface issues to be localized more quickly and fixed. Integration testing works to expose defects
in the interfaces and interaction between the integrated components (modules). Progressively
larger groups of tested software components corresponding to elements of the architectural design
are integrated and tested until the software works as a system.