Based on the scale of measurement for each variable listed below, which measure of central tendency is

Question:

Based on the scale of measurement for each variable listed below, which measure of central tendency is most appropriate for describing the data?
(a) The time (in years) it takes a sample of students to graduate college
(b) The blood type (e.g., Type A, B, AB, O) of a group of participants
(c) The rankings of college undergraduate academic programs