Governments Can Use Tariffs to Help Domestic Firms Act Like

Governments can use tariffs to help domestic firms act like a cartel when selling to international buyers:

A) if it's unlikely that other governments would impose retaliatory tariffs.
B) and if all governments do this, greater gains are realized by all countries.
C) only if international buyers have few substitutes for the domestic good.
D) but there are no actual examples of governments trying to do this.