A．the members of small groups tend to have a greater degree of social regularity than the members of large groups
B．people in small groups carry an advantage in the arena of exchange because they are tied by social obligation
C．the manufacturer of a commodity in a small group economy is more likely to be known by the members of the group
D．the people who contribute to the production of a gift are less essential to small groups than those who exchange commodities are in large groups
E．a system of social obligation diminishes the number of parties necessary to a gift-giving transaction