mark the following statements True or False and explain it. a) To avoid being exploited, poor countries should stop trading with rich countries. b) If a country has the highest productivity in every product, it can be fully "self-dependent" and does not need to trade with other countries. c) The trade in services will stagnate due to transportation difficulties. d) Even if the trade partner will not have a retaliatory tariff, introducing a tariff may still hurt domestic welfare