Taxes on goods that are underproduced are to market efficiency as subsidies on goods with negative externalities are to what?

Taxes on goods that are underproduced help to improve market efficiency by encouraging more production of those goods. Similarly, subsidies on goods that have negative externalities aim to correct market failure and promote the production of goods that benefit society. For example, if a factory produces clean energy but is not making enough profit, a subsidy can help it produce more, which benefits the environment and public health. By providing financial support, the government encourages the production of goods that have positive effects, balancing out the negative impacts of other activities. In this way, subsidies help to align private incentives with social benefits, promoting overall market efficiency.