Which describes the european theory according to mann?

Higher prices.

Explanation:

Trade barriers are those measures carried out by governments with the objective of limiting trade between the nation and other countries, either by limiting the entry of imported goods through tariffs, imposing embargoes, devaluing the currency, etc. Ultimately, any action that involves a reduction in international trade will be considered a trade barrier.

Trade barriers tend to increase the prices of goods, since they limit the competition of domestic products with imported products, which are clearly limited through increases in their final price or directly through restrictions on entering the country. Thus, less competition means greater control of prices by domestic manufacturers, which results in an upward trend in prices, while producers tend to want to obtain a greater profit taking advantage of their advantageous situation.