Final answer:
The correct statement for a matched-pair design is that the matched elements within each pair are assigned to the same treatment.
Step-by-step explanation:
The correct statement for a matched-pair design is b) The matched elements within each pair are assigned to the same treatment.
In a matched-pair design, two measurements are drawn from the same pair of individuals or objects. The goal is to compare the two measurements to see the effect of a treatment. Since the matched elements within each pair are assigned to the same treatment, statement b) is true.