Mercury is a hypothetical store that sells athletic shoes, particularly shoes for runners. Mercury is distinctive in the training of its sales staff. The store has a variety of diagnostic tools, including weight distribution analysis and slow-motion replay, and the staff are trained to use those tools to help customers figure out exactly which shoe will be best for them. Mercury also carries a wide assortment of shoes from the full range of athletic shoe makers, some of which are otherwise-hard-to find models. Although Mercury is an independent store, it is part of a buying cooperative that enables it to obtain its shoes from suppliers at volume discounts prices that would otherwise be available only to large chains. Mercury sponsors a variety of races in its greater metropolitan area, the largest of which is a high-profile annual marathon.
Of the following list of Mercury's activities, which TWO have the greatest potential for co-specialization?
a. Diagnostic skills of staff
b. Buying cooperative membership
c. Broad product assortment
d. Race sponsorship