It is given only that D ≥ E. Which pair of conclusions has the property that neither conclusion follows on its own, yet at least one of the two must be true?

D ≥ E says D is strictly above E or equal to it, and those two cases are exhaustive and mutually exclusive. So the pair 'D > E' and 'D = E' is the complementary pair: D = 9, E = 3 refutes the second, D = E = 3 refutes the first, yet one of them always holds. The pair 'D > E, D < E' is not exhaustive, because D = E is possible and would make both false — and D < E is in fact impossible here. The pair 'D ≥ E, D = E' fails the first requirement, since D ≥ E is simply the given statement and therefore already follows on its own. The pair 'D < E, D = E' is not exhaustive either, since D = 9, E = 3 makes both false.