A hospital sets up a billboard for its referral line in one city and in a second city it runs newspaper ads for its referral line in order to determine which media approach generates more telephone calls. This research method would be categorized as a:

The correct answer is observational

Observation is a constant source of knowledge for man about himself, others and the world around him. The observational method is one of the most used in the social sciences and has some curious aspects.

trade regulation is a field of law, often bracketed with antitrust (as in the phrase “antitrust and trade regulation law”), including government regulation of unfair methods of competition and unfair or deceptive business acts or practices. antitrust law is often considered a subset of trade regulation law. franchise and distribution law, consumer protection law, and advertising law are sometimes considered parts of trade regulation law.

in general the theory of economics says that the more open to trade a country is the better   the result for the same country and the whole economies.

in real life countries impose taxes, quotas, etc which is not so good for the economies.

this kind of commercial war between the usa and china is slowing down the growth of the whole world so we can say that it is a draw back of trade regulations. and the free trade agreements are benefits of trade regulations.