A survey was given to sophomores at a university and one of the questions asked was "What is the probability that you will leave school before you graduate?" The answer to this question for an individual student is an example of
A) a relative frequency probability based on long-run observation.
B) a relative frequency probability based on physical assumptions.
C) a personal probability.
D) a probability based on measuring a representative sample and observing relative frequencies that fall into various categories.