Felicia, a marketing executive of Trinola Inc., a manufacturer of nutritional supplements, visits a high school to promote Trinola's products. She conducts a survey among students and classifies them into three groups: those who do not take any nutritional supplements, those who take Trinola's nutritional supplements, and those who prefer nutritional supplements of other brands. Felicia talks to the first group about the importance of consuming nutritional supplements and to the second group about Trinola's products in detail. To the third group, she explains why Trinola's products are better than those of other brands. In this scenario, which of the following types of market segmentation does Felicia employ?