If You Were Going to Design a Study on the Rise

If you were going to design a study on the rise of peer groups, which of these topics would it make the most sense for you to investigate?

A) why peer groups of different sizes have roughly the same political clout
B) how advertising and marketing may someday make peer groups obsolete
C) the rise and fall of youth culture within affluent societies
D) how industrialization and modernization have changed learning