Final answer:
Test data sets that exercise a program in the same manner belong to the same equivalence class, which is part of a standardization method in software testing.
Step-by-step explanation:
All the sets of test data that exercise a program in the same manner are said to belong to the same equivalence class. This is a standardization method of testing where different test cases are considered equivalent if they are expected to produce the same result, exercising the same paths through the program. For example, inputting different sets of numbers that should all result in the same output from a mathematical function in a program would all be part of the same equivalence class. This concept is important because it helps testers minimize the number of test cases—instead of testing every possible input individually, they can test just one or a few inputs from each equivalence class to achieve comprehensive coverage.