Equivalence partitioning is a technique that divides the input domain into classes of data that are expected to behave similarly. The test sets should cover one value from each equivalence class, as well as the boundary values between them. The equivalence classes for the metro fare system are:

Before 9:30 am (full fare)

Between 9:30 am and 5:00 pm (saver ticket)

Between 5:00 pm and 7:00 pm (full fare)

After 7:00 pm (saver ticket)

The boundary values are 9:30 am, 5:00 pm, and 7:00 pm. Therefore, the test set that provides the best equivalence partitioning coverage is the one that includes one value from each equivalence class and the boundary values, which is option D. References =

ISTQB Certified Tester Advanced Level Syllabus Technical Test Analyst1, page 2

Boundary Value Analysis and Equivalence Partitioning Testing2, section “Equivalence Partitioning”

Equivalence Partitioning Method3, section “Example 1: Equivalence and Boundary Value”