The correct answer is: 3; tariffs do not lead to the optimal use of the scarce world resources.
Tariffs are usually imposed to protect infant or key domestic industries, to protect domestic jobs, to prevent capital flight and to equalise costs of production between domestic and foreign producers.
However, in recent years there has been a realisation that the presence of tariffs eliminates or reduces the advantages of specialisation and exchange among nations, and therefore prevents the best use of scarce world resources.
