Final answer:
A tariff decreases domestic consumption and reduces total gains from trade.
Step-by-step explanation:
A tariff is a tax imposed on imported goods. When a tariff is implemented, it usually leads to higher prices for those imported goods. As a result, domestic consumption of those goods decreases. For example, if the government imposes a tariff on imported cars, the higher prices of cars will cause people to buy fewer cars. This decrease in domestic consumption affects the total gains from trade, which refers to the overall benefits that countries can derive from engaging in international trade. When domestic consumption decreases due to a tariff, the total gains from trade are reduced because the benefits to consumers are outweighed by the increase in prices and the loss of choice.