Government intervention in markets to correct inefficiencies is to allocative efficiency as a monopsony is to:

Government intervention in markets aims to correct inefficiencies, which helps ensure that resources are distributed in a way that meets the needs of society. A monopsony, where there is only one buyer in a market, can create inefficiencies by limiting competition and driving prices down for sellers. This situation can lead to lower wages for workers or less payment for suppliers, which isn’t fair or efficient. For example, if a small town has only one employer, that employer can pay lower wages since workers have no other job options. Just like government intervention seeks to improve allocative efficiency, addressing the issues of a monopsony can help create a fairer market for everyone involved.