Critical Reasoning

For several consecutive years, poultry prices at each of three statewide grocery-store chains have exceeded the national average by about fifty percent. Also, the per-pound difference in poultry prices among the three stores never amounted to more than a few pennies, while among grocery stores in other states, the prices varied by nearly a dollar over the same period. The three chains must have conspired to not compete amongst themselves and to fix their poultry prices at mutually agreed-upon levels.

The claim that the three grocery-store chains conspired to fix poultry prices rests on which of the following assumptions for the time period referred to above?

(A) No other grocery store charged higher prices for poultry than the three chains.
(B) Average poultry prices in the state where the three chains operate exceeded the national average.
(C) The price that grocery stores paid for poultry did not vary significantly from state to state.
(D) Consumers in the state where the three chains operate generally prefer poultry over other meats even if poultry is more expensive than other meats.
(E) Other grocery stores operating in the same state as the three chains also sell poultry to consumers.