I would say that the independent variable is the violent film, as it is what is being changed in the experiment.
If a country is not able to produce some goods, it has to buy them somewhere else and bring them into the country - this is called importing, so the correct answer is b.
Selling goods outside of the country is called exporting and giving them away would be called donating.
So japan collages have Japanese language. AND CHINESE collages have Chinese languages.