Variables that are not used or improperly declared are defects that are more likely to be found by a static analysis tool than by other testing techniques, because they are syntactic or structural errors in the code that can be detected without executing the software13. A static analysis tool can analyse the code or design of the software under test and identify errors such as missing declarations, undefined variables, unused variables, or unreachable code13. The other options are not defects that are more likely to be found by a static analysis tool than by other testing techniques. Option A is not a defect that can be found by a static analysis tool, but rather by a requirements review or specification-based testing technique1 . Option B is not a defect that can be found by a static analysis tool, but rather by a structure-based testing technique or a coverage measurement tool1 . Option C is not a defect that can be found by a static analysis tool, but rather by a dynamic analysis tool or a monitoring tool1 .