In some markets for used goods:
a. the seller has more information than the buyer about the quality of the good.
b. the buyer has more information than the seller about the quality of the good.
c. the quality of used goods sold in the market will typically rise over time.
d. low-quality used goods will be underpriced.

Dr. robbins wants to know if there are different opinions regarding the value of public school education between native americans who have at least one relative who attended indian boarding school and native americans who have no family experience with indian boarding school. dr. robbins contacts 35 native american participants in each group. he wants each group to include younger as well as older adults, and a mix of male and female participants. he asks each person to complete a survey about their attitudes toward public education. the design of this study is: