Read the statements and decide which conclusion follows. Statements: X ≤ Y, Y > Z. Conclusions: I. X < Z.
II. X ≥ Z.

Both X and Z lie at or below Y, so their order is not fixed — X could be less than, equal to, or greater than Z. Conclusions I (X < Z) and II (X ≥ Z) together cover every case and are mutually exclusive, so exactly one must hold: either I or II follows.