Explain whether each of the following is an example of a macroeconomic concern or a microeconomic concern.
a. The Federal Aviation Administration (FAA) is considering increasing the number of takeoff and landing slots available at Ronald Reagan Washington National Airport.
b. The president has proposed increasing the marginal tax rate for people whose annual earnings exceed $275,000 and lowering the marginal tax rate for those who earn less than $275,000.
c. Walmart announced that it will increase its starting wage for employees to $10 per hour by February 2016.
d. Congress extends the maximum duration for the collection of unemployment benefits from 26 weeks to 52 weeks.