Identify which of the following headlines represents a microeconomic topic and which represents a macroeconomic topic.
a. "U.S. Unemployment Rate Reaches Historic Laws"
b. "General Motors Closes Auto Plant in St. Louis"
c. "OPEC Action Results in a General Increase in Prices"
d. "Companies Cut the Cost of Health Care for Employees"
e. "Lawmakers Worry About the Possibility of a U.S. Recession"
f. "Colorado Rockies Make Outfielder Highest Paid Ballplayer"