The correct answer is:
d. Free trade
Explanation:
Free trade is a policy where governments do not interfere with trade between countries, it permits free activity on imports and exports without tariffs, subsidies, quotas and prohibitions on goods between different economies. A free-trade policy helps with economic growth rates, and eliminates barriers, this policy was based on Adam Smith's theory in which he stated that countries could benefit from free trade because they would increase their productivity, quality, efficiency and specialization because the competition and the demand would require it.
Nowadays free-trade between countries are based on free-trade agreements where governments impose taxes to protect their local producers, but to help consumers get the best quality.
