Social barriers refer to trade protection measures taken by a country under the pretext of the working environment and the right to life of workers in other countries in international trade. Which of the following are social barriers. ['Country A considers that the employment of agricultural workers in Country B is serious, and therefore cancels trade orders with that country.', 'Country A terminates the trade when it finds that a certain heavy metal content exceeds the limit in milk powder imported from country B.', 'Country A was affected by the economic crisis, and a large number of domestic workers were unemployed. In order to create employment opportunities for workers, the government of Country A terminated its import trade with many countries.', 'Country A believes that the quality of the employees in the automobile manufacturing industry of Country B is low, which will affect the safety of the automobile, so it has cancelled the order to import cars from Country B.']