Which testing activity focuses on verifying a single component or unit of code in isolation?

• A. Xml
• B. Unit Testing
• C. Update
• D. While Loop

Answer: (B)

Verifying a single component or unit of code in isolation is unit testing. It focuses on small, self-contained pieces of functionality—like a function or method—and tests them independently from the rest of the system. Tests provide controlled inputs and assert expected outputs, with any external dependencies replaced by test doubles (mocks or stubs) so the test targets only the unit’s behavior. This approach helps catch bugs early, makes debugging easier, and supports safer refactoring.

The other options aren’t testing activities: XML is a data format, Update is an operation that changes software, and a While Loop is a programming construct used for repetition.