In economics, abstraction from reality is necessary because of the complexity of the real world

In recent years new automobile factories have opened in California and Ohio and closed in Detroit where the unemployment of automobile workers has increased. This unemployment could be decreased if

A) "moving costs" from Detroit to California and Ohio were reduced. B) information about the new jobs was made available to the unemployed workers at reduced cost. C) workers with the appropriate skills were relatively scarce in Ohio and California. D) all of the above.

Explain why wage rates might rise at Joe's Quik-Print Shop if Joe replaces his aging copy machines with state-of-the-art copy machines