Final answer:
The positions of runners in a race would be measured on an ordinal scale (Option D).
Step-by-step explanation:
The positions of runners in a race represent an ordinal scale of measurement since they denote a ranking order without specifying the magnitude between the ranks. This is because the positions can be ordered by rank. For example, first place, second place, third place, and so on.
However, the differences between the positions don't denote a fixed measurement of performance or time; that is to say, the difference between first and second place is not necessarily the same as the difference between second and third place. Therefore, the level of measurement of the variable 'Positions of runners in a race' is ordinal.
Thus, the correct option is D.