Scenario - the Audrey Firm

Scenario - The Audrey Firm
The Audrey Firm is an international trade consulting firm currently providing its services in eight foreign nations.The primary goal of this company is to prevent trade missteps from taking place between foreign nations conducting business with each other.The participating nations prefer to seek counsel with this firm before any of their actions result in major international involvement or World Trade Organization intervention.
In the past,the Audrey Firm's team of experts has handled international situations having the potential to create serious unrest between neighboring countries.Their guidance and expertise have been successful in keeping trade operating freely in several areas of the globe.The Audrey Firm is receiving an award for their exemplary service later this year in Washington D.C.
-The clients of the Audrey Firm use various techniques to restrict imports to their countries.Which one of the following assigns a fixed amount of tax for every physical unit imported?

A) Import quota
B) Voluntary export restraint
C) Ad valorem tariff
D) Specific tariff
E) Domestic content provision