Answer
a) The goal of an oligopolist buyer is to decrease the price paid for an item.
b) The goal for the owners is to limit how much each team pays for their players. This will be difficult to control since players can leave teams and be paid more by a different team in the league. (Thus, owners have no incentive to remain in the cartel.)
Work Step by Step
c) The salary cap would have made formal the collusion between the owners and tried to help limit any team from cheating the cartel.