Research into genetically modified crops has led to significant productivity gains for countries such as the United States that employ these techniques. Countries such as the European Union member nations, however, have imposed controls on the import of these products, citing concern for public health. Given the situation, the European Union's regulation of genetically modified crops is

A$.$ a rate of return regulation.

B$.$ a cost of service regulation.

C$.$ a social regulation.

D$.$ an economic regulation.