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 definition aligns with achieving thorough code coverage, ensuring that all parts of the code have been exercised by tests. However, it is important to note that complete testing in a practical sense is rarely achievable, as it assumes exhaustive testing of all possible scenarios. Reference: ISTQB CTFL Syllabus V4.0, Section 4.3.2​​.