Final answer:
The correct answer is A) Classes / Select / 75% / Source / Target, pertaining to software testing requirements where selected classes must have a minimum code coverage.
Step-by-step explanation:
The question pertains to a feature found in software development and testing environments. The correct completion for the sentence based on typical testing requirements would be: Only the classes you select will be run. If this option is selected, a minimum of 75% of code coverage in each of the source and target to which the test level will be applied must be covered. This involves specifying which classes are to be included in the test run and ensuring that a sizable portion of the code is tested to maintain quality.