Final answer:
Option (A), 90% statement coverage in software testing means that 90% of the code's executable statements have been executed by the tests, which provides a high level of confidence in the testing process, analogous to confidence intervals in statistics that contain the true mean.
Step-by-step explanation:
When a set of tests has achieved 90% statement coverage, it means that 9 out of 10 statements have been exercised by this set of tests. This does not refer to decision outcomes, the number of tests run, or the correctness of requirements statements about the software. Instead, it is specifically about the proportion of executable statements in the code that have been executed or evaluated at least once during the testing process.
To provide a clearer context in the field of software testing, let's consider an analogy with statistics. Ninety percent confidence intervals are often mentioned in statistics. If we took repeated samples, approximately 90 percent of the confidence intervals calculated from those samples would contain the true value of the population mean. Similarly, in software testing, achieving 90% statement coverage gives us confidence that a significant portion of the code has been tested, reducing the likelihood of undetected errors.