To answer this question, you need to understand the concept of software testing.
Option A) Regression Testing - This option is correct. Regression testing is the process of retesting the entire application or a subset of it after a change has been made to ensure that the change has not introduced any new defects or caused any existing functionality to break.
Option B) Unit Regression - This option is incorrect. Unit testing is a type of testing that focuses on testing individual units or components of the application, not the entire application. Unit regression testing is not a commonly used term in software testing.
Option C) Regional Regression - This option is incorrect. "Regional regression" is not a recognized term in software testing. It does not refer to the process of retesting the entire application after a change has been made.
Option D) Retesting - This option is incorrect. Retesting refers to the process of rerunning test cases that previously failed to verify whether defects have been fixed. It does not necessarily involve retesting the entire application after a change has been made.
The correct answer is A) Regression Testing. This option is correct because it accurately describes the process of retesting the entire application after a change has been made to ensure that the change has not introduced any new defects or caused any existing functionality to break.