Variance from programming standards defects (option (A)) are found during the review or static testing process. Therefore a test harness is unlikely to find a defect in programming standards.
Memory leak defects (option (C)) could potentially be found by a test harness designed to run many test cases.
Regression defects (option (D)) could be found using many types of test tool.
Defects in middleware (option (B)) are generally more likely to be found by a test harness or a dynamic analysis tool than by any other type of tool.