Which is the best definition of complete testing?

Complete testing is best defined as having tested every statement, branch, and combination of branches in the program. This approach ensures comprehensive coverage of the program's code and logic, which is essential for identifying potential defects. By testing every aspect of the code, including all possible paths that execution might take, the likelihood of undiscovered bugs is significantly reduced.

This definition emphasizes the importance of thoroughness in testing activities. It reflects the concept that to achieve completeness in testing, one must ensure that all logical reasoning flows through the program have been evaluated. This is particularly relevant in understanding code complexity and ensuring that the testing effort validates the behavior of the software in all conceivable scenarios.

Other options may imply certain levels of completeness but do not encompass the rigorous standards required for comprehensive testing. Discovering every bug does not guarantee that all possible scenarios have been evaluated, testing all statements and branches goes further to ensure thoroughness, meeting a deadline does not necessarily correlate with completeness, and merely completing tests outlined in a test plan could leave untested scenarios if the plan was not comprehensive in the first place.