It is a fact that there are 24 million left-handed people in the United States, however, most marketers do not attempt to appeal to or design products for this group because there is little in the way of census data about this group. Therefore, this group fails in one of the requirements for effective segmentation. Which of the following is most likely to apply in this case?
a. actionable
b. substantial
c. differentiable
d. measurable