Your answer is regulations. Though the government doesn't have lots of control over the free market system they can still regulate to an extent. For example the market cannot produce and sell illegal goods.
HI Fakemcacc
The answer is A
Hope this helps!:D
-MalStar
I believe the demand for automobiles in the 1920s stimulated growth in many other industries. Think of the other things that came after automobiles. ;)