If Zeta could credibly threaten to run a high advertising budget, then Zeta could deter Alpha from choosing High, because Alpha would earn less than Zeta in that case. Zeta would prefer to run a Low advertising budget and earn 2000, but if Alpha chooses High, then Zeta would switch to High and earn 1000, while Alpha would earn 1000 as well. This would make Alpha indifferent between choosing High or Low, so Zeta could try to buy out Alpha and operate as a monopoly. The maximum Zeta would be willing to pay Alpha in this situation would be 1000, which is the difference between Zeta's profit under monopoly (2000) and Zeta's profit under competition (1000). The minimum Alpha would be willing to accept to be bought out in this situation would be 1000, which is Alpha's profit under competition. Therefore, the range of possible buyout prices is [1000, 1000], which means that Zeta could buy out Alpha for exactly 1000 and both parties would be indifferent