Please help with the following international trade question:

Please mark the following statements True or False (there is no "it depends") and explain in 1-2 sentences. (a) A country is less productive in every kind of product, and then it will only be hurt in trade. (b) Free trade with countries that pay low wages still benefits high-wage countries. (c) The growth in the international service trade is stagnant due to the difficulty in transportation. (d) Even without a retaliatory tariff, introducing a tariff may still hurt domestic welfare